ECM-4201 - Three-way catalytic converter (TWC) efficiency. Power deterioration
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:
7 modelsC70 Cabriolet (1998–2005), C70 Coupé (1998–2002), S60 (2001–2009), S70 (1997–2000), S80 (1999–2006), V70 (1997–2000), V70 (2000–2008)
Show models by year and engine (18)
- Volvo C70 Cabriolet (1998–2005)2000Engine B5244S only
- Volvo C70 Coupé (1998–2002)1999Engine B5254S DENSO only
- Volvo C70 Coupé (1998–2002)2000Engine B5244S only
- Volvo S60 (2001–2009)2001–2002, 2009Engine B5244S, B5244S2 only
- Volvo S60 (2001–2009)2003–2005Engine B5244S, B5244S2, B5244S6, B5244SG, B5244SG2 only
- Volvo S60 (2001–2009)2006Engine B5244S, B5244S2, B5244S6, B5244SG only
- Volvo S60 (2001–2009)2007–2008Engine B5244S, B5244S2, B5244SG only
- Volvo S70 (1997–2000)1999Engine B5254S DENSO only
- Volvo S70 (1997–2000)2000Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo S80 (1999–2006)1999–2000Engine B5244S, B5244S2 only
- Volvo S80 (1999–2006)2001, 2006Engine B5244S, B5244S2, B5244SG only
- Volvo S80 (1999–2006)2002–2005Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo V70 (1997–2000)1999Engine B5254S DENSO only
- Volvo V70 (1997–2000)2000Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo V70 (2000–2008)2001, 2007–2008Engine B5244S, B5244S2, B5244SG only
- Volvo V70 (2000–2008)2002Engine B5244S, B5244S2, B5244SG, B5244SG2 only
- Volvo V70 (2000–2008)2003–2005Engine B5244S, B5244S2, B5244S6, B5244SG, B5244SG2 only
- Volvo V70 (2000–2008)2006Engine B5244S, B5244S2, B5244S6, B5244SG only
What does this fault code mean?
After start-up the engine control module tests the catalytic converter's efficiency by alternating between rich and lean mixture and seeing how quickly the rear oxygen sensor reacts. If the sensor switches too quickly, the module interprets this as the catalytic converter having deteriorated. The fault can come from exhaust gas leakage, damaged fuel injectors or a damaged catalytic converter.
Possible causes
- Air leak in the exhaust system
- One or more damaged fuel injectors
- Damaged catalytic converter
What you can do
- 1Check the exhaust system for air leaks at joints and connections
- 2Repair any leak found and clear the fault code
- 3On some engines from model year 2001 to 2002, all fuel injectors should be replaced if the fault remains; have a workshop do this
- 4Have you got a diagnostic tool: watch in live data how the rear oxygen sensor switches while the engine runs under even load
- 5Have a workshop replace the catalytic converter if the fault remains after the other checks have been made
Symptoms you may notice1
- Malfunction indicator lamp (MIL) is on
General guidance for car owners. Diagnosis on the car can point to a different cause.