What does it mean?
This diagnostic trouble code (DTC) is a generic powertrain code, meaning it applies to OBD-II equipped vehicles. Although generic, specific repair steps may vary by make/model.
The TPS (Throttle Position Sensor) is a potentiometer mounted on the throttle body. It detects the throttle blade angle. As the throttle blade moves, the TPS sends a signal to the PCM (Powertrain Control Module). Typically a three-wire sensor: a 5-volt reference from PCM to TPS, a ground from PCM to TPS, and a signal return from TPS to PCM.
The TPS returns throttle position information to the PCM on this signal wire. When the throttle is closed, the signal is near 0.45 volts. At WOT (Wide Open Throttle), the TPS signal voltage will approach a full 5 volts. When the PCM detects a voltage outside the normal operating range, P0225 sets. The C refers to a particular circuit, a sensor, or an area of a particular circuit.
NOTE: The PCM knows that any significant change in throttle position means a corresponding change in intake manifold pressure (MAP) response. On some models, the PCM will monitor MAP and TPS operation for comparison. This means if the PCM sees a significant percentage change in throttle position, it expects to see a simultaneous response change in intake manifold pressure and vice versa. If it does not see this comparative change, P0225 may be set. This does not apply to all models.
Symptoms
Potential symptoms include:
MIL (Malfunction Indicator Lamp) illumination
Misfires at idle or highway speed
Poor idle quality
May not idle
May start and stall
Causes
Potential causes of code P0225 include:
Sticking throttle return spring
Corrosion on MAP or TPS connectors
Misrouted harness causing chafing
Faulty TPS
Faulty PCM
Possible Solutions
If you have access to a scan tool, with KOEO (Key On Engine Off), monitor the TPS voltage. With the throttle closed, the voltage should be around 0.45 volts. It should gradually sweep up to about 4.5 to 5 volts as you press the throttle. Sometimes only an oscilloscope can capture an intermittent problem in the TPS signal voltage. If you notice a problem in the TPS sweep voltage, replace the TPS.
NOTE: Some TPS sensors require fine adjustment. If you are not comfortable using a DVOM (Digital Volt Ohm Meter) to adjust the new TPS, then it is best to take the vehicle to a shop. If the voltage is not 0.45 volts (+ or – about 0.3 volts) with the throttle closed or if the reading is “stuck,” disconnect the TPS connector. With KOEO, check for the 5-volt reference voltage present at the connector and a good ground. You can check the signal circuit continuity by jumpering a fused wire between the TPS connector ground circuit and the signal circuit. If the TPS reading on the scan tool now reads zero, replace the TPS. However, if it does not change the reading to zero, check for an open or short in the signal wire and if none are found, suspect a faulty PCM. If manipulating the TPS wiring harness causes a change at rest, suspect a faulty TPS.