VOLVO
ECM-401C - Three-way catalytic converter (TWC) efficiency, bank 2. Signal too high
System
Engine Control Module (ECM)
Volvo models this fault code applies to
Applies to the following models:
5 modelsS60 (2001–2009), S80 (1999–2006), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
Show models by year and engine (10)
- 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 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 efficiency of the catalytic converter on bank 2 deviates too much, according to the engine control module. It compares the values from the rear and front oxygen sensors, and the code is set under certain driving conditions when the difference becomes too large. The cause may be misfiring, a leak, faulty fuel pressure, uneven compression or a damaged catalytic converter.
Possible causes
- Misfiring
- Leakage in the intake system
- Leakage in the exhaust system
- Faulty fuel pressure
- Uneven compression
- Damaged catalytic converter
What you can do
- 1Look for leaks in the intake system hoses and in the exhaust system joints and gaskets
- 2Check the spark plugs for damage to the insulation, since misfiring can cause the same fault
- 3Have a workshop check fuel pressure, residual pressure and compression with diagnostic equipment
- 4Read the code and see whether it returns after a test drive
- 5If the fault remains: have a workshop try a new oxygen sensor and then a new catalytic converter
Symptoms you may notice1
- Malfunction indicator lamp is lit
What the fault can affect1
- Rear long-term fuel trim is disabled
General guidance for car owners. Diagnosis on the car can point to a different cause.