What does it mean?
P1544 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Throttle Actuation Potentiometer Signal Too High .
Symptoms
- Check engine light on with reduced power or limp mode
- High or surging idle, or an engine that revs up on its own briefly
- Throttle response uneven, with a lurch when pulling away
- Engine speed limited during acceleration
- Cruise control unavailable
- Fault may appear when the engine is hot and disappear when cold
Likely causes
- Open sensor ground circuit, so the signal rises towards reference voltage
- Signal wire shorted to the five volt reference or to battery voltage
- Worn potentiometer track that breaks contact near the end of its travel
- Corroded connector terminals at the throttle body creating high resistance
- Throttle plate held partly open by carbon or a damaged return mechanism
- Harness chafed against a bracket close to the throttle body
- Module input circuit failure as the last suspect
How to fix it
- Watch both throttle position signals in live data while sweeping the pedal, and note which one is high
- Carry out a voltage drop test on the sensor ground and measure the five volt reference
- Unplug the sensor and check the signal wire for a short to reference or supply voltage
- Inspect the connector for corroded, spread or backed-out terminals
- Inspect the harness near the throttle body for chafing against brackets
- Clean the throttle bore and check the plate returns fully, then perform the relearn procedure
- Replace the throttle body or potentiometer if the signal stays high with the wiring proven good