VOLVO
ECM-U007300 - Control module communication bus "A" Off. General Failure Information. No sub type information
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
14 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), S60 (2011–), S80 (2007–), V40 (2013–), V40 Cross Country (2013–), V50 (2004–2013), V60 (2011–), V60 Cross Country (2015–), V70 (2008–), XC60 (2009–), XC70 (2008–), XC90 (2003–)
Show models by year and engine (24)
- Volvo C30 (2007–2013)2011–2013Engine D5204T, D5204T5 only
- Volvo C70 (2006–2013)2011Engine D5204T, D5204T5 only
- Volvo C70 (2006–2013)2012–2013All engines except: B5254T7
- Volvo S40 (2004–2013)2011–2012Engine D5204T, D5204T5 only
- Volvo S60 (2011–)2011–2012All engines except: B5254T5, D4162T
- Volvo S60 (2011–)2013–2015All engines except: D4162T
- Volvo S80 (2007–)2010Engine B4204T6, B6324S, B8444S, D5244T10, D5244T14, D5244T19 only
- Volvo S80 (2007–)2011All engines except: B4204S3, B4204S4, B5254T10, B5254T11, B5254T8, D4164T
- Volvo S80 (2007–)2012All engines except: B5254T10, D4162T
- Volvo S80 (2007–)2013–2015All engines except: D4162T
- Volvo V40 (2013–)2013–2015All engines except: D4162T
- Volvo V40 Cross Country (2013–)2013–2015All engines except: D4162T
- Volvo V50 (2004–2013)2011–2012Engine D5204T, D5204T5 only
- Volvo V60 (2011–)2011–2015All engines except: D4162T
- Volvo V60 Cross Country (2015–)2015
- Volvo V70 (2008–)2010Engine B4204T6, B6324S, D5244T10, D5244T14, D5244T19 only
- Volvo V70 (2008–)2011All engines except: B4204S3, B4204S4, B5254T10, B5254T11, D4164T
- Volvo V70 (2008–)2012All engines except: B5254T10, D4162T
- Volvo V70 (2008–)2013–2015All engines except: D4162T
- Volvo XC60 (2009–)2010All engines except: B6304T2, B6324S2
- Volvo XC60 (2009–)2011–2015
- Volvo XC70 (2008–)2010All engines except: B6304T2, B6324S2
- Volvo XC70 (2008–)2011–2015
- Volvo XC90 (2003–)2011–2014Engine B6324S5 only
What does this fault code mean?
The code means that the engine control module (ECM) has disconnected itself from the CAN network, which is called bus-off. It is set when the module detects that CAN communication is blocked by a serious disturbance, which may come from the wiring, the connectors or another control module on the network.
Possible causes
- Contact resistance or oxidation in the connectors
- Open circuit in one of the CAN network wires
- One or more CAN wires are shorted to ground, voltage or each other
- Internal fault in the ECM
- Internal fault in another control module on the same part of the CAN network
What you can do
- 1Read the code with a diagnostic tool and check whether it is active or only stored
- 2Look at the codes in the other control modules; if they also show communication faults, the fault is probably in the network
- 3Check the connections on the CAN network at the engine control module for contact resistance and oxidation
- 4If you have a diagnostic tool: clear the codes, drive the car for a while and read whether the communication fault comes back
- 5Tell the workshop if anything has recently been done to the car's electrical system or to a control module, since this may have affected the CAN network
- 6Have a workshop measure the resistance and voltage on the CAN network and find the control module that is disturbing it
Symptoms you may notice5
- Red warning symbol and text message in the display
- The engine hesitates, surges or jerks on acceleration and after engine braking
- Uneven idling
- Cruise control does not work
- The engine does not start, either sometimes or all the time
What the fault can affect3
- Engine torque may be limited
- The engine control module stops communicating on the CAN network and switches itself off
- The engine control module stays off until the voltage supply has been broken, and makes new attempts to communicate when the voltage is connected again
General guidance for car owners. Diagnosis on the car can point to a different cause.