Code
P2135
AUDI
P — Powertrain
Accelerator Pedal Position (APP) assembly failure, Powertrain Control Module (PCM) failure, Throttle Position Sensor (TPS) failure, Wiring issue
Views:
UK: 24
EN: 142
RU: 56
AI status
Completed
Completed
100%
Causes
- Faulty accelerator pedal position (APP) sensor/module
- Faulty throttle position sensor (TPS) or electronic throttle body
- Damaged wiring harness or connector (open, short to power/ground, high resistance, corrosion)
- Poor or intermittent connector pin contact
- Failed or intermittent PCM/engine control module
- Water ingress or contamination at pedal or throttle connectors
Symptoms
- MIL (Check Engine) illuminated
- Reduced engine power / limp-home mode engaged
- Poor throttle response, hesitation or surging
- Engine may not respond to accelerator pedal or shows delayed response
- Stored freeze-frame data showing pedal/throttle signal mismatch
What to check
- Read all stored DTCs and freeze-frame data with a capable scan tool
- Record live data: APP sensor channels and TPS channel while key on and while varying pedal/throttle
- Verify ignition key state and throttle control inputs during code set (some systems require learning/reset after battery disconnect)
- Visually inspect connectors and wiring for damage, corrosion, water, or loose pins at APP, throttle body and PCM
- Wiggle test wiring harness while observing live sensor values for intermittent changes
- Check for other related codes (CAN bus, power supply, ground faults)
Signal parameters
- 5 V reference supply expected on sensor reference circuit (verify at connector)
- Sensor outputs typically vary between ~0.5–4.5 V from closed to wide-open; both APP channels should change smoothly and proportionally
- Secondary APP/TPS channel should track the primary channel within a small offset and show expected correlation (no sudden divergence)
- At key on (engine off) some sensors will show a parked/closed voltage; compare to manufacturer spec
Diagnostic algorithm
- Connect a professional scan tool and record stored codes, freeze-frame, and live APP/TPS data. Note when the code set and under what conditions.
- Attempt to reproduce the fault while monitoring live data: press pedal slowly to full travel and observe both APP channels and TPS for smooth, correlated movement.
- Visually inspect APP and throttle body connectors and wiring for damage, corrosion, or water intrusion. Repair any visible damage.
- Back-probe the sensor connectors: with key ON (engine off) verify 5 V reference, signal voltages, and ground continuity. Compare voltages to expected range and check that both APP channels move proportionally.
- Perform a wiggle test on wiring and connectors while watching live data to locate intermittent short/open or high-resistance joints.
- If wiring and connectors check good, unplug sensors one at a time and observe behavior per factory procedure (some vehicles will log additional codes; follow OEM steps).
- Check continuity from sensor signal pins to the PCM and check for shorts to battery or ground. Repair any open/shorts found.
- If wiring and sensors test within spec, follow manufacturer procedure to test/replace throttle body or APP module. Replace the failed component only after verifying cause.
- After repair, clear codes, perform any required relearn/initialization procedure (throttle/A/T learn), and road-test to confirm the fault does not return.
- If fault persists after replacing sensors and repairing wiring, evaluate PCM operation or replace/flash only per factory guidance (consider PCM as last resort).
Likely causes
- Damaged/loose connector or pin at APP or throttle body (most common)
- Wiring harness chafing or short to ground/power
- Failed APP sensor assembly
- Failed throttle position sensor or throttle body motor assembly
- Intermittent PCM input circuit fault (least common)
Fault status
Status
PCM detected inconsistent or implausible correlation between accelerator pedal position and throttle position sensor signals; control strategy reduced engine power and set MIL.
Repair difficulty: Medium
Diagnostic time: 1-3 hours
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