Throttle/Pedal Position Sensor/Switch C Circuit Intermittent
Code P0229 indicates an intermittent fault in the Throttle Position Sensor (TPS) "C" circuit, which measures throttle valve position for engine control. This intermittent signal disruption causes the PCM to lose reliable throttle input, affecting fuel delivery and ignition timing.
What You Might Notice
- Hesitation or stumbling during acceleration
- Black or excessive smoke from exhaust on startup
- Delayed or rough engine cranking, especially in cold weather
- Check Engine Light illuminated
- Possible limp mode or reduced engine power
Most Common Causes
- 1
Defective Throttle Position Sensor
The TPS itself may be failing internally with intermittent contact, causing signal dropout. A worn or degraded sensor is the most common cause of this code.
- 2
Corroded or Loose TPS Connectors
Moisture and corrosion on the TPS electrical connector or wiring terminals can create intermittent poor connections. Loose pins in the connector are also a frequent culprit.
- 3
Damaged TPS Wiring
The wiring harness between the TPS and PCM may have a break, short, or pinch point causing intermittent signal loss. Vibration or engine heat can aggravate damaged insulation.
- 4
Binding or Stuck Throttle Plate
A throttle plate that sticks or binds can cause the TPS to send erratic readings. Carbon buildup or mechanical wear in the throttle body may cause this binding.
How to Diagnose It
- 1
Check Defective Throttle Position Sensor — The TPS itself may be failing internally with intermittent contact, causing signal dropout. A worn or degraded sensor is the most common cause of this code.
- 2
Check Corroded or Loose TPS Connectors — Moisture and corrosion on the TPS electrical connector or wiring terminals can create intermittent poor connections. Loose pins in the connector are also a frequent culprit.
- 3
Check Damaged TPS Wiring — The wiring harness between the TPS and PCM may have a break, short, or pinch point causing intermittent signal loss. Vibration or engine heat can aggravate damaged insulation.
- 4
Check Binding or Stuck Throttle Plate — A throttle plate that sticks or binds can cause the TPS to send erratic readings. Carbon buildup or mechanical wear in the throttle body may cause this binding.
How to Fix It
- 1
Inspect and Clean TPS Connector
Disconnect the TPS connector and inspect for corrosion, moisture, or loose pins. Clean with electrical contact cleaner and reconnect firmly. Check for proper seating and weatherproofing.
- 2
Test and Replace Throttle Position Sensor
Use a multimeter to test the TPS output voltage while gently moving the throttle. If voltage is erratic or drops intermittently, replace the sensor. Proper adjustment or relearning may be required after replacement.
- 3
Inspect TPS Wiring Harness
Trace the wiring from the TPS connector to the PCM, checking for cuts, abrasions, pinches, or moisture intrusion. Repair or replace damaged sections and secure wiring away from hot engine components.
- 4
Clean Throttle Body and Check Plate Movement
Remove and inspect the throttle body for carbon buildup or mechanical binding. Clean thoroughly with throttle body cleaner and verify smooth throttle plate operation through full range.
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