What does it mean?
P1242 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Throttle Valve Control Motor 2 Circuit Malfunction .
Symptoms
- Check engine lamp on together with limp mode and reduced power
- Engine will not rev past a low limit, throttle response is dead
- Erratic or hunting idle, sometimes a stall when coming to rest
- Uneven running if only one of two throttle units responds
- Fault often appears after washing the vehicle or in wet conditions
Likely causes
- Motor winding open, shorted or with resistance outside specification
- Damaged wiring between the module and the second throttle motor
- Water or corrosion in the connector, especially on units mounted low or exposed to spray
- Throttle plate binding from carbon or a mechanical fault, overloading the motor
- Fuse or supply feed to the second throttle circuit open
- Loose or missing ground for the throttle unit
- Module output stage failure
How to fix it
- Read the codes from the engine module and note whether both throttle motors are reported
- Check the fuse and measure supply voltage at the second throttle unit connector
- Inspect that connector for water, corrosion and terminal damage, then dry and clean it
- Measure the motor winding resistance and compare it with the first unit
- Actuate the throttle with the scan tool and watch whether the position signal follows the command
- Remove and clean the throttle bore and confirm the plate moves without binding
- Repair the wiring, then replace the throttle unit only if the motor itself tests faulty, and perform the relearn
- Assess the module driver as the final step