P0229

Code

Generic P — Powertrain

Throttle/Pedal Position Sensor/Switch C Circuit Intermittent

Brand: Generic

Type: P — Powertrain

Views: UK: 29 EN: 41 RU: 34

AI status

Completed

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Page language: EN

Causes

Damaged or loose wiring or connector on the TPS/pedal sensor C circuit
Corroded or contaminated connector pins
Intermittent internal failure of the throttle position or accelerator pedal position sensor (sensor C)
Poor reference voltage or ground (intermittent 5V reference or ground)
Intermittent ECM/instrument cluster input circuit problem
Aftermarket accessories or recent repairs that disturbed harness routing

Symptoms

Check Engine Light (MIL) illuminated intermittently
Erratic throttle response, hesitation or surging during acceleration
Possible fail-safe/limp mode activation (reduced power) under some conditions
Unpredictable idle speed or stalling in severe cases
Code returns intermittently, may not be present every key cycle

What to check

Read freeze-frame and live data with a scan tool — note conditions when code set (RPM, throttle %, vehicle speed, voltage)
Check for related codes (other TPS/pedal circuits, throttle actuator codes, power/ground faults)
Visually inspect sensor connector and wiring for damage, corrosion, pin push-back or water
Wiggle harness and connectors while watching live data to try to reproduce the fault
Confirm reference voltage (typically ~5 V) and ground stability at sensor with engine on
Inspect for recent service or aftermarket work near harness that could have disturbed wiring

Signal parameters

Reference voltage to sensor: typically ~5.0 V (may vary slightly by manufacturer)
Signal voltage (idle) typical: ~0.5–1.0 V depending on design; at wide open throttle typical: ~4.0–4.5 V
Switch circuits (if present) should be stable open/closed; intermittent toggling indicates fault
Continuity: sensor signal to ECU should be < a few ohms; unexpected high resistance or intermittent open possible
No large voltage spikes or dropouts on signal line during normal operation

Diagnostic algorithm

Use a scan tool and confirm P0229 is current or stored. Record freeze-frame and live PID values for sensor C, reference voltage and grounds.
Perform a visual inspection of the pedal/throttle sensor connector and wiring harness for chafe, heat damage, pin corrosion, or loose terminals.
Backprobe the sensor signal, reference and ground with key on (engine off) and with engine running. Verify stable ~5V reference and ground continuity to chassis/ECU.
Monitor the sensor C signal on a scan tool or multimeter while moving the throttle/pedal through full travel. Look for smooth, monotonic change; note any dropouts or spikes.
While monitoring live data, gently wiggle wiring, connectors and move harness sections to try to reproduce the intermittent fault. If code reappears, isolate area of failure.
If intermittent is still not reproduced, use an oscilloscope if available to check for intermittent noise, spikes, or grounding issues on the signal line under load/with vibration.
If wiring appears suspect, perform continuity and resistance checks from sensor C signal pin to ECU pin (key off). Repair any opens, high resistance, or shorted conductors.
If wiring and connector are good but signal remains intermittent, replace the pedal/throttle position sensor assembly. Some systems require throttle/accelerator adaptation after replacement — follow manufacturer procedure.
If replacement does not clear the issue, inspect/replace the ECU connector or consider ECU input circuit diagnosis (refer to manufacturer service information) before replacing ECU.
After repair, clear codes and perform a test drive under conditions that previously set the code to verify repair. Re-scan to ensure code does not return.

Likely causes

Broken/frayed wire in harness near harness chafe points or movable joints
Connector with water intrusion/corrosion causing intermittent contact
Sensor internal worn contacts or intermittent electronics
Loose pin at ECM or sensor terminal
Intermittent short to battery or to ground under engine vibration

Fault status

⚠️ Status

Intermittent fault detected on Throttle/Pedal Position Sensor/Switch C circuit — signal was unstable or toggled outside expected limits. Investigate sensor, wiring, connectors, reference voltage and ECU input.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours