Code
P1158
DS
P — Powertrain
Electric throttle signal malfunction
Views:
UK: 1
EN: 2
RU: 2
AI status
Completed
Completed
100%
Causes
- Faulty throttle position sensor (TPS) or accelerator pedal position sensor (APPS)
- Open/short or poor connection in throttle/accelerator wiring harness or connectors
- Corroded or damaged electrical connector pins
- Blown fuse or faulty relay in throttle control/ECU supply
- Faulty throttle body assembly (actuator/motor or internal gearing)
- Low battery voltage or poor charging system
Symptoms
- Check Engine / MIL illuminated
- Reduced engine power / limp-home mode
- Poor or delayed throttle response, hesitation
- Stalling or inability to hold idle in some cases
- Unusual throttle behavior on pedal input (surging, stuck)
- Possible driveability faults stored in ECU memory
What to check
- Read and record all stored DTCs, freeze frame and live data with a capable scanner
- Check battery voltage and charging system (while cranking and at idle)
- Inspect fuses and relays related to ECU and throttle control
- Visual inspection of throttle body, connectors and wiring for damage/corrosion
- Backprobe throttle and pedal sensor connectors and check reference, signal and ground
- Operate throttle with scan tool to observe commanded vs actual throttle angle
Signal parameters
- Reference voltage to sensors: typically ≈5.0 V (check vehicle spec)
- Typical TPS/APPS output range: approx. 0.2–4.8 V across travel
- Closed/throttle-off signal: often ≈0.5–1.0 V (sensor dependent)
- Wide-open throttle signal: often ≈4.0–4.5 V (sensor dependent)
- Some systems use two TPS/APPS channels with inverse or correlated voltages — both channels must correlate within manufacturer tolerance
- Watch for unstable voltage, spikes, or loss of signal during operation
Diagnostic algorithm
- Retrieve DTCs and freeze-frame data. Note conditions when fault set (engine temp, rpm, throttle position).
- Check battery voltage (should be ~12.6 V resting, >13.5 V with engine running). Repair charging/battery faults first.
- Inspect fuses, relays and grounds related to throttle/ECU. Repair any obvious issues.
- Visually inspect throttle body and pedal harness/connectors for damage, corrosion or pin push-out. Repair as needed.
- Using a scan tool, view live TPS/APPS signals and commanded throttle. Verify reference 5 V, ground, and signal voltages. Compare both channels for expected correlation.
- Perform a wiggle test on harness/connectors while monitoring live data to find intermittent opens/shorts.
- If signal voltages are out of range, backprobe and measure voltage at sensor and at ECU connector to isolate harness vs ECU.
- If wiring is good and voltages are incorrect at sensor, replace the sensor/throttle body assembly per manufacturer procedure.
- If sensor and wiring test good but fault persists, consider ECU software update or ECU replacement after manufacturer guidance.
- Clear codes, perform throttle relearn/adaptation if required, and road test to confirm repair.
Likely causes
- Wiring harness damage or connector corrosion at throttle body
- Faulty throttle position sensor or pedal position sensor
- Throttle body actuator/motor malfunction
- Low battery voltage or poor ground
- Intermittent connector contact causing signal dropouts
Fault status
Status
Electric throttle signal malfunction detected. ECU sees invalid or inconsistent throttle/pedal position signals or actuator response. May cause reduced power / limp mode until fault is resolved.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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