VOLVO
TCM-0121 - Control unit. Internal fault
System
Transmission Control Module (TCM)
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 modelsS40 (1996–2004), S60 (2001–2009), S80 (1999–2006), V40 (1996–2004), V70 (2000–2008), V70 XC / XC70 (2001–2007), XC90 (2003–)
Show models by year and engine (17)
- Volvo S40 (1996–2004)2001–2004
- Volvo S60 (2001–2009)2001–2002
- Volvo S60 (2001–2009)2003All transmissions except: M58
- Volvo S60 (2001–2009)2004–2009Transmission AW50/51 AWD, AW55-50/51SN only
- Volvo S80 (1999–2006)1999–2000Transmission AW55-50/51SN only
- Volvo S80 (1999–2006)2001–2006Transmission AW50/51 AWD, AW55-50/51SN only
- Volvo V40 (1996–2004)2001–2004
- Volvo V70 (2000–2008)2000–2002
- Volvo V70 (2000–2008)2003All transmissions except: M58
- Volvo V70 (2000–2008)2004–2007Transmission AW50/51 AWD, AW55-50/51SN only
- Volvo V70 (2000–2008)2008Transmission AW55-50/51SN only
- Volvo V70 XC / XC70 (2001–2007)2001–2002
- Volvo V70 XC / XC70 (2001–2007)2003–2007Transmission AW50/51 AWD only
- Volvo XC90 (2003–)2003All transmissions except: 4T65 AWD
- Volvo XC90 (2003–)2004–2007Transmission AW50/51 AWD, AW55-50/51SN only
- Volvo XC90 (2003–)2008–2014Transmission AW50/51 AWD only
- Volvo XC90 (2003–)2015
What does this fault code mean?
The control module has registered a fault within itself in the circuit that drives the solenoids. When it occurs, activation of the solenoids is cut off, so gear changes become harsh or do not occur.
Possible causes
- Internal fault in the control module
What you can do
- 1Read and clear the fault code, road test and see whether it returns
- 2If you have a diagnostic tool: activate solenoids S4 and S5 one at a time and check that each changes between off and on
- 3Have a workshop replace the control module and program it, since a new module is supplied without software
- 4After the replacement, a workshop should check that the fault has been cleared
Symptoms you may notice5
- The orange general warning lamp is lit
- The malfunction indicator lamp is lit
- The lock-up function does not work
- Harsh gear changes
- Gear changes do not occur
What the fault can affect1
- The transmission limp-home program Limp-home is activated
General guidance for car owners. Diagnosis on the car can point to a different cause.