VOLVO
ECM-950C - Accelerator pedal (AP) position sensor. Faulty signal
System
Engine Control Module (ECM)
Volvo models this fault code applies to
This fault code has different meanings depending on model, model year or engine. Select the meaning that applies to your car.
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (8)
- Volvo C30 (2007–2013)2007–2011Engine B5244S4 only
- Volvo C70 (2006–2013)2006All engines except: B5254T3
- Volvo C70 (2006–2013)2007–2010Engine B5244S4, B5244S5 only
- Volvo C70 (2006–2013)2011Engine B5244S4 only
- Volvo S40 (2004–2013)2004Engine B5244S4, B5244S5 only
- Volvo S40 (2004–2013)2005–2010Engine B5244S4, B5244S5, B5244S7 only
- Volvo V50 (2004–2013)2004Engine B5244S4, B5244S5 only
- Volvo V50 (2004–2013)2005–2010Engine B5244S4, B5244S5, B5244S7 only
What does this fault code mean?
The ECM compares the PWM signal, which runs directly to it, with the analog signal that comes via the central electronic module (CEM) and CAN. The code is stored when the ECM detects a fault in either signal from the accelerator pedal sensor. If one signal is faulty, the other is used.
Possible causes
- Fault in the central electronic module (CEM), where fault tracing starts
- PWM signal cable shorted to voltage or ground, or broken
- Loose connections or contact resistance in the PWM or analog signal terminals
- Damaged accelerator pedal position sensor
- Fault in the voltage supply or ground to the accelerator pedal sensor
- Fault in the CAN communication between the ECM and the CEM
What you can do
- 1Read the fault codes in the CEM first and deal with them. This code cannot be cleared until the CEM code has been remedied and cleared
- 2Check the accelerator pedal sensor and ECM connectors for play, contact resistance and oxidation
- 3If you have a diagnostic tool: activate the read-out of the accelerator signals with the ignition on, and compare the values with the pedal untouched and pressed down
- 4Use a multimeter to check the PWM signal cable, and the supply and ground to the analog signal, for breaks and shorts
- 5If the fault remains, have a workshop with diagnostic equipment decide whether the accelerator pedal sensor needs replacing. Accelerator input is ignored when braking, so do not keep driving with the fault
Symptoms you may notice4
- Poor accelerator pedal response
- Accelerator pedal ignored when braking
- Message in the information display
- Vehicle's maximum speed limited
What the fault can affect3
- The accelerator pedal signal is filtered when accelerating
- Accelerator input is ignored when braking
- If one signal fails, the other signal is used
General guidance for car owners. Diagnosis on the car can point to a different cause.