VOLVO
ECM-821B - System relay. Signal missing
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
8 modelsC70 (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 (13)
- Volvo C70 (2006–2013)2006Engine B5254T3 only
- Volvo S40 (2004–2013)2005–2006Engine B5254T3 only
- Volvo S60 (2001–2009)2005–2006Engine B5204T5, B5244T4, B5244T5, B5254T2, B5254T4 only
- Volvo S80 (1999–2006)2005–2006Engine B5204T5, B5244T4, B5254T2, B6294S2, B6294T only
- Volvo V50 (2004–2013)2005–2006Engine B5254T3 only
- Volvo V70 (2000–2008)2005Engine B5204T5, B5244T4, B5244T5, B5254T2, B5254T4 only
- Volvo V70 (2000–2008)2006Engine B5204T5, B5244T5, B5254T2, B5254T4 only
- Volvo V70 XC / XC70 (2001–2007)2005All engines except: D5244T
- Volvo V70 XC / XC70 (2001–2007)2006Engine B5244T4, 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?
The ECM monitors the feed through the system relay and finds it too low. The fault may come from the charging system, contact resistance in the connections, a break in the signal wire or a damaged relay. The starter cranks but the engine will not run.
Possible causes
- Faulty charging system
- Contact resistance in the connections
- Break in the signal wire to the system relay
- Damaged system relay
What you can do
- 1Check the battery voltage and condition
- 2Look for loose or corroded connectors at the system relay
- 3Using a multimeter, check that the signal wire to the system relay is not broken
- 4Check that the generator charges, as a faulty charging system can cause the fault
- 5If the fault remains, have a workshop try a new system relay
Symptoms you may notice1
- The starter cranks but the engine does not start
General guidance for car owners. Diagnosis on the car can point to a different cause.