VOLVO
ECM-P040937 - Exhaust Gas Recirculation Sensor A Circuit. FM (Frequency Modulated) / PWM (Pulse Width Modulated) Failures. Signal frequency too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsS80 (2007–), V70 (2008–), XC60 (2009–), XC70 (2008–), XC90 (2003–)
Show models by year and engine (6)
- Volvo S80 (2007–)2007–2009Engine D5244T4, D5244T5 only
- Volvo V70 (2008–)2008–2009Engine D5244T4, D5244T5 only
- Volvo XC60 (2009–)2009All engines except: B6304T2
- Volvo XC70 (2008–)2008All engines except: B6324S
- Volvo XC70 (2008–)2009Engine D5244T4, D5244T5 only
- Volvo XC90 (2003–)2013–2014Engine D5244T18, D5244T5 only
What does this fault code mean?
The code is named for a signal frequency that is too high. It is set when the PWM signal from the position sensor on EGR valve A is incorrect, and the ECM monitors that signal while the engine runs.
Possible causes
- Loose contact or oxidation in the connectors
- Break in the signal cable
- Damaged position sensor
- Damaged EGR valve
- EGR valve sticking from soot or dirt
- Fault codes ECM-P040936 and ECM-P040938 may share the same cause
What you can do
- 1Check the signal cable for chafing and pinching, since it carries the position sensor signal
- 2Check that the connectors to the position sensor are firm and free from oxidation
- 3If you have a diagnostic tool, read the fault status with the engine running and see whether the fault is active
- 4Check that the EGR valve moves without sticking and clean it of soot if needed
- 5Read and clear the fault code, then road test the car to see whether it comes back
- 6If the fault remains, have a workshop check the position sensor and the EGR valve
Symptoms you may notice1
- The Check engine (malfunction indicator) light comes on or behaves abnormally
What the fault can affect1
- EGR control is lost
General guidance for car owners. Diagnosis on the car can point to a different cause.