Throttle/Pedal Position Sensor/Switch "E" Circuit Intermittent
Code P2129 indicates the PCM detected an intermittent signal in the Throttle Position Sensor/Switch E circuit, meaning the sensor is not sending consistent voltage readings. This intermittent condition prevents the engine computer from accurately determining throttle position, affecting fuel injection timing and engine performance.
What You Might Notice
- Hesitation or stumbling during acceleration
- Black smoke from exhaust on startup
- Delayed or difficult cold starts
- Rough idle or erratic engine behavior
- Check Engine Light illuminated
Most Common Causes
- 1
Loose or corroded TPS connector
The Throttle Position Sensor connector may be partially disconnected, corroded, or have intermittent contact causing signal dropout. This is the most common cause of intermittent circuit codes.
- 2
Damaged or frayed TPS wiring
The wiring harness between the TPS and PCM may have breaks, cracks, or exposed wire causing intermittent connection loss, especially during vibration or temperature changes.
- 3
Defective Throttle Position Sensor
The TPS itself may have an internal intermittent fault or worn potentiometer that causes signal loss under certain conditions or throttle positions.
- 4
Binding or damaged throttle plate
A stuck or misaligned throttle plate may cause the TPS to send erratic signals when the throttle binds during movement.
How to Diagnose It
- 1
Check Loose or corroded TPS connector — The Throttle Position Sensor connector may be partially disconnected, corroded, or have intermittent contact causing signal dropout. This is the most common cause of intermittent circuit codes.
- 2
Check Damaged or frayed TPS wiring — The wiring harness between the TPS and PCM may have breaks, cracks, or exposed wire causing intermittent connection loss, especially during vibration or temperature changes.
- 3
Check Defective Throttle Position Sensor — The TPS itself may have an internal intermittent fault or worn potentiometer that causes signal loss under certain conditions or throttle positions.
- 4
Check Binding or damaged throttle plate — A stuck or misaligned throttle plate may cause the TPS to send erratic signals when the throttle binds during movement.
How to Fix It
- 1
Inspect and clean TPS connector
Locate the Throttle Position Sensor connector and inspect for corrosion, bent pins, or loose connections. Clean with electrical contact cleaner and reseat firmly until you hear a click.
- 2
Check TPS wiring harness
Visually inspect the entire wiring harness from the TPS to the PCM for cuts, abrasions, pinches, or exposed conductors. Repair or replace any damaged sections and secure harness away from heat sources.
- 3
Replace Throttle Position Sensor
If connector and wiring are intact, remove the TPS fasteners and disconnect the sensor. Install a new OEM or quality aftermarket TPS unit, adjust if necessary per manufacturer specs, and verify code clears.
- 4
Inspect throttle body and plate
Remove the throttle body and inspect the throttle plate for damage, carbon buildup, or binding. Clean with throttle body cleaner and ensure smooth free movement through full range.
Need a deeper diagnosis?
Search for related repair guides or browse by system.