VOLVO
ECM-929D - Engine control module (ECM). Signal too low
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
9 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), S60 (2001–2009), S80 (1999–2006), V50 (2004–2013), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
Show models by year and engine (23)
- Volvo C30 (2007–2013)2007Engine B5254T3 only
- Volvo C30 (2007–2013)2008–2013Engine B5254T7 only
- Volvo C70 (2006–2013)2006–2007Engine B5254T3 only
- Volvo C70 (2006–2013)2008–2013Engine B5254T7 only
- Volvo S40 (2004–2013)2005–2007Engine B5254T3 only
- Volvo S40 (2004–2013)2008Engine B5254T3, B5254T7 only
- Volvo S40 (2004–2013)2009–2012Engine B5254T7 only
- Volvo S60 (2001–2009)2005–2006Engine B5204T5, B5244T4, B5244T5, B5254T2, B5254T4 only
- Volvo S60 (2001–2009)2007Engine B5204T5, B5244T5, B5254T2, B5254T4 only
- Volvo S60 (2001–2009)2008–2009Engine B5204T5, B5244T5, B5254T2 only
- Volvo S80 (1999–2006)2005–2006Engine B5204T5, B5244T4, B5254T2, B6294S2, B6294T only
- Volvo V50 (2004–2013)2005–2007Engine B5254T3 only
- Volvo V50 (2004–2013)2008–2012Engine B5254T7 only
- Volvo V70 (2000–2008)2005Engine B5204T5, B5244T4, B5244T5, B5254T2, B5254T4 only
- Volvo V70 (2000–2008)2006–2007Engine B5204T5, B5244T5, B5254T2, B5254T4 only
- Volvo V70 (2000–2008)2008Engine B5254T2 only
- Volvo V70 XC / XC70 (2001–2007)2005All engines except: D5244T
- Volvo V70 XC / XC70 (2001–2007)2006Engine B5244T4, B5254T2 only
- Volvo V70 XC / XC70 (2001–2007)2007Engine B5254T2 only
- Volvo XC90 (2003–)2005–2006Engine B5254T2, B6294T only
- Volvo XC90 (2003–)2007–2012Engine B5254T2 only
- Volvo XC90 (2003–)2013–2014Engine B5254T9 only
- Volvo XC90 (2003–)2015
What does this fault code mean?
This code concerns the ECM's internal governor that controls the throttle angle, although it is titled signal too low. The ECM stores it if the governor is found damaged, or if the governor's control signal goes to an extreme while the throttle is being controlled. It is checked with the engine running and can be permanent or sporadic.
Possible causes
- The throttle sticks or is blocked by oil film or dust
- Contact resistance or oxidation in the connections between the ECM and the throttle unit
- Open circuit, or short to ground or supply voltage, in the wiring to the throttle motor
- The throttle motor wires shorted to each other
- Damaged throttle unit
- Faulty software in the ECM
What you can do
- 1If you have a diagnostic tool: read the fault status with the engine running. Fault found means permanent, and No fault found means sporadic and not active right now
- 2Check the connectors between the ECM and the throttle unit: are they secure, and is there oxidation or corrosion
- 3Make sure the throttle moves freely and is not blocked by any object. Clean as needed
- 4Use a multimeter on the throttle motor wires for open circuit, contact with ground or plus, and a short between the two wires
- 5If you have a diagnostic tool: after a repair, check in the parameters that the throttle unit adaptation is complete and shows OK. The adaptation is carried out by a workshop
- 6If the fault remains, faulty software in the ECM may be the cause. A workshop can download and install new software
Symptoms you may notice2
- Malfunction indicator lamp (MIL) on
- Reduced performance
What the fault can affect2
- The ECM cuts power to the throttle motor, and the throttle goes to its spring-loaded return position
- The fuel supply may be temporarily cut off, and this shut-off is reversible
General guidance for car owners. Diagnosis on the car can point to a different cause.