Code
P1688
ALFA ROMEO
P — Powertrain
Motorised throttle (2ndidlelearn)
Views:
UK: 22
EN: 67
RU: 20
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
CHRYSLER
P — Powertrain
Internal Fuel Injection Pump Controller Failure
Views:
UK: 25
EN: 42
RU: 31
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
DODGE
P — Powertrain
Internal Fuel Injection Pump Controller Failure
Views:
UK: 26
EN: 49
RU: 29
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
FIAT
P — Powertrain
Motorised throttle (2ndidlelearn)
Views:
UK: 22
EN: 30
RU: 19
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Similar codes
Repair manuals
Manual library for FIAT
17
Browse 17 FIAT manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
FIAT
-
FIAT: 2021
-
500X
-
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Code
P1688
JEEP
P — Powertrain
Internal Fuel Injection Pump Controller Failure
Views:
UK: 28
EN: 47
RU: 32
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
MAZDA
P — Powertrain
Metering Oil Pump Stepping Motor Cont Circuit
Views:
UK: 25
EN: 44
RU: 32
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
MINI
P — Powertrain
Electronic throttle control monitor level 2/3 - MAF calculation
Views:
UK: 18
EN: 23
RU: 22
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Similar codes
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Code
P1688
Other
P — Powertrain
Metering Oil Pump Stepping Motor Circuit Malfunction
Views:
UK: 24
EN: 43
RU: 27
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Similar codes
Repair manuals
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Code
P1688
PLYMOUTH
P — Powertrain
Internal Fuel Injection Pump Controller Failure
Views:
UK: 21
EN: 37
RU: 27
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P1688
PONTIAC
P — Powertrain
Internal Fuel Injection Pump Controller Failure
Views:
UK: 25
EN: 39
RU: 26
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
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0
Send to email
Code
P1688
RAM
P — Powertrain
Internal Fuel injection pump controller failure
Views:
UK: 23
EN: 29
RU: 20
AI status
Completed
Completed
100%
Causes
- Failed or sticking motorised throttle body
- Throttle position sensor or potentiometer fault
- Corroded/damaged wiring or connector at throttle body
- Low or unstable battery/charging voltage during learn procedure
- Carbon build-up or mechanical obstruction on throttle plate
- Faulty ECU or corrupted adaptation memory/software bug
Symptoms
- Check Engine Light (MIL) illuminated
- Unstable or high/low idle speed
- Engine stalling at idle or after cold start
- Reduced engine power or limp-home mode in some cases
- Hesitation or poor throttle response during idle/low speed
What to check
- Read and record all stored and pending DTCs and freeze-frame data with a capable scan tool
- Check battery voltage and charging system (minimum ~12.2 V with key on; >13.5 V running)
- Perform key-on engine-off (KOEO) throttle actuator self-test with diagnostic tool and observe throttle plate movement
- Monitor live data: actual throttle angle/position vs. commanded target while performing actuator tests
- Inspect throttle body connector and wiring for corrosion, damage, pin push-out or water ingress
- Visually inspect and, if necessary, clean throttle plate and bore for carbon deposits
Signal parameters
- Throttle plate actual angle (degrees)
- Throttle plate target/commanded angle
- Throttle position sensor voltage (V) or %
- Throttle actuator motor current or status (if available)
- Accelerator pedal position A/B voltages
- Battery voltage during learn procedure
Diagnostic algorithm
- Connect a professional scan tool, read and save all stored, pending and history codes and freeze-frame data.
- Verify battery state-of-charge and charging system. Recharge or replace weak battery and ensure stable voltage before testing.
- Visually inspect throttle body connector and wiring for damage, corrosion and secure connector retention. Repair any wiring faults.
- Run a KOEO/KOER throttle actuator test from the diagnostic tool and observe mechanical operation and position feedback. Note any binding or asymmetry.
- Monitor live data: compare commanded throttle angle vs actual during actuator exercise and while operating accelerator pedal. Look for erratic or no feedback.
- Clean the throttle plate and bore if heavy carbon is present, then repeat actuator test and adaptation attempt.
- Follow manufacturer procedure to perform the 2nd idle / throttle adaptation (relearn). Clear codes, perform the relearn with stable battery voltage and recheck for codes.
- If adaptation fails and wiring, power and cleaning are good, bench-test or replace the throttle body assembly and then perform the relearn procedure.
- If replacing throttle body does not resolve, inspect/reflash ECU software and check for ECU faults or other control module interference. Consider manufacturer technical service bulletins.
- After repair, clear codes, perform required relearns, road-test and confirm no return of the fault.
Likely causes
- Throttle actuator motor worn or seized
- Open/short in throttle harness pins (motor, position sensor, heater)
- Low battery voltage during key-on or relearn attempt
- Throttle plate heavily carboned preventing full motion
- Missing or incomplete throttle adaptation after throttle body replacement or battery disconnect
Fault status
Status
P1688 — Motorised throttle (2nd idle learn) failed. Throttle adaptation incomplete or not verified. Check throttle body, wiring, battery voltage and perform throttle relearn.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email