Throttle/Pedal Position Sensor/Switch A Circuit Malfunction
What does this mean?
Code P0120 indicates a malfunction in the Throttle Position Sensor (TPS) 'A' circuit. The PCM monitors the TPS to determine throttle blade angle.
Disclaimer: This diagnostic code is part of the standard OBD2 system and can apply to Nissan Gt-r models manufactured from 1996 to 2026. However, please note that the presence of this specific code depends on your vehicle's exact engine configuration, options, and production year.
Common Causes
Faulty throttle position sensor (TPS)
Damaged, chafed, or broken wiring harness
Corroded or loose electrical connector
Dirty or faulty throttle body
Symptoms to Watch For
- Check Engine Light is illuminated
- Poor acceleration or sluggish response
- Engine surging or fluctuating RPM
- Engine stalling or dying unexpectedly
- Erratic or fluctuating idle speed
- Vehicle enters reduced power / limp mode
How to Diagnose
Common Solutions
Replace the Throttle Position Sensor (TPS): This is the most common fix if the sensor itself is found to be faulty after voltage signal verification. Ensure the replacement part is of high quality, preferably OEM or a reputable aftermarket brand, as cheap sensors can quickly fail or provide inaccurate readings.
Repair or Replace Damaged Wiring/Connectors: If the diagnostic steps reveal damaged, corroded, or shorted wiring, or compromised connector terminals, these must be repaired or replaced. Use appropriate automotive-grade wiring and connectors, ensuring proper soldering and heat-shrink insulation for durable, long-lasting repairs.
Clean Throttle Body: If the throttle plate is sticking due to carbon buildup, it can put undue stress on the TPS or cause the PCM to interpret the sensor's output as erratic, especially if the sensor is integrated into the throttle body assembly. A thorough cleaning can restore smooth operation and prevent future issues.
PCM Software Update or Replacement: In rare cases, if all other components and wiring test perfectly, the issue might lie within the Powertrain Control Module itself. A PCM software update (reflash) might resolve a known calibration issue, or in extreme cases, the PCM may need to be replaced if its internal TPS driver circuit has failed. This should only be considered after exhausting all other diagnostic avenues.