Code
P0725
Generic
P — Powertrain
Engine Speed Input Circuit
Views:
UK: 17
EN: 23
RU: 21
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Workshop Manuals
Available brands with manuals
2
AUDI 11
6-speed manual gearbox 0B1, front-wheel drive — Workshop Manual (Edition 05.2014)
Workshop Manual199,00 UAH
Audi A3 (1997) – 1.6L 4-cylinder (2‑valve) Engine Mechanical Components Service Manual (AEH, AKL, APF) – Edition 07.2002
Workshop Manual199,00 UAH
AUDI A3 (2004) Workshop Manual — 2.0L FSI Turbo (4‑cyl, 4‑valve) Engine, Mechanics — Edition 03.2017
Workshop Manual199,00 UAH
Audi A3 2004 — Electrical System (Workshop Manual, Edition 02.2018)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet – 4.2 l V8 (5‑valve, timing chains) – Workshop Manual (Mechanics) – Edition 04.2007
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet — Auxiliary Heater Workshop Manual (Edition 08.2004)
Workshop Manual199,00 UAH
Audi A4 / A4 Cabriolet (1.8T 4‑cyl turbo) — Motronic Injection & Ignition System Service Manual (Edition 01.2015)
Workshop Manual199,00 UAH
Audi A8 (2003) — Electrical System Workshop Manual (Edition 08.2014)
Workshop Manual199,00 UAH
Audi Q4 e-tron (Type F4) - Self-study Programme SSP 685
Workshop Manual199,00 UAH
Audi Q8 (2018) — Electrical System Workshop Manual (Edition 05.2019)
Workshop Manual199,00 UAH
Audi Servicing Manual — 7‑Speed Dual Clutch Transmission 0CJ / 0CL / 0CK / 0DN / 0DP / 0HL (Edition 05.2018)
Workshop Manual199,00 UAH
LAND ROVER 3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
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Code
P0725
GWM
P — Powertrain
- Engine speed sensor circuit fault
Views:
UK: 2
EN: 3
RU: 8
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P0725
HUMMER
P — Powertrain
Engine Speed Input Circuit
Views:
UK: 6
EN: 9
RU: 13
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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Code
P0725
LAND ROVER
P — Powertrain
Engine speed input circuit
Views:
UK: 6
EN: 8
RU: 11
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
HTML Workshop Manuals AI manual library for LAND ROVER Click to show available manuals 1
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HTML ManualWorkshop Manuals
Repair manuals for LAND ROVER
3
Land Rover Defender 300Tdi — Workshop Manual (1996 model year)
Workshop Manual199,00 UAH
Land Rover Defender Workshop Manual Supplement & Body Repair Manual (1999 & 2002 MY)
Workshop Manual199,00 UAH
Land Rover Range Rover — Electrical Library (LRL 0453ENG, 2002)
Workshop Manual199,00 UAH
Your experience will help others
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0
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Code
P0725
MERCEDES-BENZ
P — Powertrain
Engine Speed input Circuit Malfunction
Views:
UK: 11
EN: 17
RU: 16
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
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HTML ManualYour experience will help others
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Code
P0725
MITSUBISHI
P — Powertrain
Crank angle sensor
Views:
UK: 5
EN: 11
RU: 10
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Your experience will help others
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Was this AI description helpful?
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👍 Like
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0
Send to email
Code
P0725
OPEL
P — Powertrain
CAN-Bus No Communication with ECM (Engine Control Module)
Views:
UK: 5
EN: 7
RU: 8
AI status
Completed
Completed
100%
Causes
- Faulty engine speed/engine RPM sensor (crank or cam sensor used for engine speed)
- Damaged wiring harness or corroded connector between sensor and PCM/TCM
- Open or short to power/ground on the sensor circuit
- Intermittent connector contact or bent pins
- Faulty PCM/TCM or internal circuit failure
- Incorrect sensor air gap, magnetized/contaminated sensor or damaged reluctor ring/tooth
Symptoms
- MIL/Check Engine lamp illuminated
- Erratic or harsh transmission shifting, delayed shifts or limp-in mode
- Tachometer may read erratically or not at all
- Cruise control may not function
- Reduced engine or drivability performance in some vehicles
What to check
- Scan for stored/active codes and freeze frame data; record engine RPM reported by PCM and TCM, if available
- Compare live engine RPM from PCM/engine ECU with tachometer and TCM input using a scan tool
- Visually inspect sensor, harness and connectors for damage, corrosion or loose pins
- Back-probe sensor connector and check for proper reference voltage, signal and ground
- Measure continuity and resistance of sensor circuit to the module and check for short to battery or ground
- Use an oscilloscope to examine sensor waveform (shape, amplitude, frequency) while cranking and at idle
Signal parameters
- Typical sensor signal: digital square wave or sinusoidal AC depending on sensor type (Hall-effect vs. magnetic pickup)
- Voltage levels: Hall sensors typically switching 0–5V (logic low/high); magnetic pickups produce AC voltage that increases with RPM
- Expected waveform: clean, stable pulses with consistent amplitude and period proportional to engine speed
- Frequency calculation: frequency (Hz) = (pulses per crank revolution × engine RPM) / 60 — verify expected pulses per rev for vehicle
- Signal should be present while cranking and at idle; no constant 0V or constant rail indicates open/short
Diagnostic algorithm
- Read and record all DTCs and freeze frame. Clear codes and attempt to reproduce while monitoring live RPM data from engine ECU and transmission module.
- Visually inspect sensor, harness and connector. Repair any obvious damage. Ensure connector is fully seated and pins are straight.
- Back-probe sensor connector. With ignition on/engine cranking, verify reference power (if applicable), ground and signal presence. Compare to expected ranges.
- Use an oscilloscope to view waveform at the sensor output while cranking and at idle. Look for clean edges (Hall) or consistent AC amplitude (magnetic).
- Check continuity between sensor and module connectors; check for short to battery or ground. Wiggle harness while monitoring signal to find intermittent faults.
- Inspect reluctor/tooth wheel and sensor air gap. Repair or replace damaged reluctor or correct gap per manufacturer spec.
- If wiring, connector and reluctor are good, substitute a known-good sensor or module (if vehicle-specific service information supports) or repair/replace sensor.
- After repairs, clear codes and road-test to verify faults do not return and that RPM reported to transmission is stable and correct.
- If signal and wiring check good and fault persists, consult manufacturer service information for module bench tests or update/flash PCM/TCM software as required.
Likely causes
- Broken or chafed sensor wire near engine or harness flex point
- Connector corrosion or a disconnected connector
- Sensor failed due to heat or contamination
- Reluctor ring tooth missing/damaged or heavy metal buildup on reluctor
- Poor ground at module or sensor reference ground
Fault status
Status
P0725 — Engine Speed Input Circuit: Transmission/PCM detected a missing, implausible or intermittent engine RPM input signal from the engine speed sensor or engine control module.
Repair difficulty: Medium
Diagnostic time: 1.0 - 3.0 hours
Your experience will help others
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Was this AI description helpful?
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0
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