Code
P1226
FIAT
P — Powertrain
Accelerator pedal movement
Views:
UK: 2
EN: 9
RU: 9
AI status
Completed
Completed
100%
Causes
- Faulty accelerator pedal position sensor/module (APPS)
- Damaged or corroded wiring or connector between pedal and ECM
- Poor ground or lost 5V reference supply to pedal sensor
- Intermittent contact due to worn/plastic parts or water ingress in connector
- Pedal mechanical binding or return-spring failure
- Faulty throttle body/drive-by-wire actuator or its wiring
Symptoms
- MIL/Check Engine lamp illuminated
- Reduced engine power or limp-home mode (limited throttle response)
- Hesitation or sudden changes in engine response when pressing pedal
- Inconsistent or jerky acceleration
- Inability to accelerate normally; vehicle may limit RPM
What to check
- Retrieve all stored DTCs and freeze-frame data with a scan tool
- Observe live data: accelerator pedal position sensor channels (usually two) while slowly moving the pedal
- Compare two pedal sensor signals for correlation and expected inverse/linear behavior
- Visually inspect pedal assembly, wiring harness and connector for damage, corrosion, water entry or debris
- Perform a wiggle test of wiring and connector while watching live data for intermittent changes
- Measure reference voltage (usually ~5V) and ground at pedal connector with key on, engine off
Signal parameters
- Reference supply typically ~5.0 V ±0.25 V to pedal sensor
- Sensor outputs (typical): Sensor A ~0.2–0.8 V at rest, rising to ~3.8–4.8 V at full travel
- Sensor B (redundant) often opposite: ~3.8–4.8 V at rest, falling to ~0.2–0.8 V at full travel
- Both sensor outputs should change smoothly and linearly with pedal travel and maintain proper correlation (no sudden jumps)
- No open circuit (OL) on signal or reference wiring and continuity to ECM pins
Diagnostic algorithm
- Connect a capable scan tool and record freeze-frame and live data for both pedal position channels; note any inconsistencies, jumps or implausible values.
- Visually inspect pedal module, connector, and harness for corrosion, bent pins, water, chafing or mechanical interference.
- With key ON (engine off), verify reference voltage (~5 V) and ground at the pedal connector. If missing, trace back wiring to fuse/ECM ground.
- Measure both pedal sensor output voltages at rest and while slowly operating the pedal. Verify linear change and proper inverse/correlated behavior between sensors.
- Perform wiggle test on harness and connector while watching live data to reveal intermittent faults.
- Check continuity and resistance of signal, reference and ground circuits between pedal connector and ECM to rule out opens/shorts. Repair any damaged wiring/connectors.
- Inspect pedal for mechanical binding, damaged return spring or excessive play; repair or replace as required.
- If wiring and pedal are good but fault persists, check throttle body/actuator and related circuits; consult manufacturer service data for pedal/ECM calibration or relearn procedures.
- If replacement of pedal module is performed, follow any required programming/relearn steps, clear codes, and road test to confirm repair.
- If problem remains after harness and module replacement, evaluate ECM for fault or consult dealer technical support/TSBs.
Likely causes
- Failed accelerator pedal module
- Open/short or intermittent wiring/connector to pedal sensor
- Loss of sensor reference or ground causing inconsistent signals
Fault status
Status
ECM detected implausible or out-of-range accelerator pedal movement signal(s). Throttle response may be reduced; service required.
Repair difficulty: Medium
Diagnostic time: 0.5-2 hours
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