VOLVO
ECM-959F - Accelerator pedal (AP) position sensor. Faulty signal. Intermittent fault
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:
5 modelsC70 Cabriolet (1998–2005), C70 Coupé (1998–2002), S70 (1997–2000), V70 (1997–2000), V70 XC (1998–2000)
Show models by year and engine (10)
- Volvo C70 Cabriolet (1998–2005)1999, 2001–2002
- Volvo C70 Cabriolet (1998–2005)2000All engines except: B5244S
- Volvo C70 Coupé (1998–2002)1999All engines except: B5254S DENSO
- Volvo C70 Coupé (1998–2002)2000All engines except: B5244S
- Volvo C70 Coupé (1998–2002)2001–2002
- Volvo S70 (1997–2000)1999Engine B5204T3, B5204T4, B5234T3, B5234T7, B5254T only
- Volvo S70 (1997–2000)2000Engine B5204T3, B5204T4, B5234T3, B5234T7, B5244T only
- Volvo V70 (1997–2000)1999Engine B5204T3, B5204T4, B5234T3, B5234T7, B5234T8, B5254T only
- Volvo V70 (1997–2000)2000All engines except: B5244S, B5244S2, B5244SG, B5244SG2, D5252T MSA 15.8
- Volvo V70 XC (1998–2000)1999–2000
What does this fault code mean?
The fault is intermittent, meaning it has occurred at some point but may not be present now. The engine control module (ECM) compares the analogue signal from the accelerator pedal sensor with the PWM signal that the throttle module sends over the CAN network. If they differ too much for a longer time while engine speed is high, the code is stored.
Possible causes
- Loose connections or contact resistance on the digital PWM signal wire
- Interference on the CAN signal wires
- The PWM wire between the engine control module and the throttle module is faulty
- Defective electronic throttle module
What you can do
- 1Read the fault code counter and freeze-frame values. They show how often the fault has occurred and the conditions when it was first detected
- 2Inspect the connectors on the PWM wire to the throttle module. Loose contact or oxidation can cause faults that come and go
- 3If you have a diagnostic tool: follow the analogue and PWM pedal values in live data while the pedal moves, and see whether they differ in an irregular way
- 4Check the CAN wires for chafing and contact problems, since interference there can affect the signal
- 5After repair: clear the code and let the ignition stay off for a while before test driving, so the throttle module resets
Symptoms you may notice2
- Poor accelerator pedal response
- Cruise control does not work at all
What the fault can affect3
- The throttle closes when braking, and the pedal position is ignored
- Cruise control is switched off for the driving cycle in which the fault was detected
- After a restart the function is back, if the fault is no longer active
General guidance for car owners. Diagnosis on the car can point to a different cause.