VOLVO
ECM-C168 - Communication, brake control module (BCM). Signal too low
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:
3 modelsC30 (2007–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (13)
- Volvo C30 (2007–2013)2007–2009Engine B4184S11, B4184S8, B4204S3 only
- Volvo C30 (2007–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo C30 (2007–2013)2011–2013Engine B4204S3, B4204S4 only
- Volvo S40 (2004–2013)2005Engine B4184S11 only
- Volvo S40 (2004–2013)2006Engine B4184S11, B4184S8 only
- Volvo S40 (2004–2013)2007–2009Engine B4184S11, B4184S8, B4204S3 only
- Volvo S40 (2004–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo S40 (2004–2013)2011–2012Engine B4204S3, B4204S4 only
- Volvo V50 (2004–2013)2005Engine B4184S11 only
- Volvo V50 (2004–2013)2006Engine B4184S11, B4184S8 only
- Volvo V50 (2004–2013)2007–2009Engine B4184S11, B4184S8, B4204S3 only
- Volvo V50 (2004–2013)2010Engine B4184S11, B4184S8, B4204S3, B4204S4 only
- Volvo V50 (2004–2013)2011–2012Engine B4204S3, B4204S4 only
What does this fault code mean?
This code covers a signal that is too low in the communication between the engine control module and the brake control module (BCM). The brake control module controls ABS, and the engine does not start while the fault is active. The fault lies in the CAN wiring or in another control module on the same part of the network.
Possible causes
- Open circuit in one of the CAN wires
- Short circuit between the CAN wires
- Internal fault in another control module on the same network section
What you can do
- 1Read out the fault codes in the brake control module (BCM) and the CEM first, and fix the CAN codes before erasing anything
- 2Check that the fuses are intact and that the battery has a good charge
- 3Check the connectors at the engine control module and the brake control module for loose contacts and corrosion
- 4Look for chafing and breaks on the CAN wires running to the brake control module
- 5Erase the code once the faults are fixed, then road test the car to see whether it comes back
- 6The brake control module controls ABS. If the brakes or ABS feel uncertain, do not drive the car until a workshop has checked them
Symptoms you may notice1
- The engine does not start
General guidance for car owners. Diagnosis on the car can point to a different cause.