VOLVO
ECM-929C - Engine control module (ECM). Signal too high
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?
Although the code is titled signal too high, it concerns the ECM's internal governor for the throttle angle. The code is stored when that governor is damaged, or when its control signal reaches an extreme while the throttle is being controlled. The fault may be permanent or sporadic.
Possible causes
- The throttle sticks or is blocked by oil film, dust or similar
- Contact resistance or oxidation between the ECM and the throttle unit
- Open circuit, or short to ground or supply voltage, in the throttle motor wiring
- Short circuit between the throttle motor wires
- A 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 that the connectors at the throttle unit and the ECM are secure and free from corrosion
- 3Check that the throttle moves freely, is not blocked by any object and is not sticking. Clean as needed
- 4Use a multimeter on the throttle motor wiring after open circuits, contact with ground or plus, and shorts between the wires
- 5If you have a diagnostic tool: check in the parameters that the throttle unit adaptation is complete and shows OK. The adaptation itself is carried out by a workshop
- 6The code can be caused by faulty software in the ECM. Checking and installing new software is a workshop job
Symptoms you may notice2
- Malfunction indicator lamp (MIL) on
- Reduced engine performance
What the fault can affect1
- The ECM cuts power to the throttle motor so the throttle goes to its return position, or the fuel supply is temporarily shut off
General guidance for car owners. Diagnosis on the car can point to a different cause.