VOLVO
TCM-0420 - Shift fork 1 blocked. No movement on any other shift fork.
System
Transmission Control Module (TCM)
Volvo models this fault code applies to
Applies to the following models:
4 modelsC30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)
Show models by year and engine (10)
- Volvo C30 (2007–2013)2008Engine D4204T only · Transmission MPS6 only
- Volvo C30 (2007–2013)2009–2010Engine B4204S3, D4204T only · Transmission MPS6 only
- Volvo C30 (2007–2013)2011–2013Engine B4204S3 only · Transmission MPS6 only
- Volvo C70 (2006–2013)2009–2010Engine D4204T only · Transmission MPS6 only
- Volvo S40 (2004–2013)2008Engine D4204T only · Transmission MPS6 only
- Volvo S40 (2004–2013)2009–2010Engine B4204S3, D4204T only · Transmission MPS6 only
- Volvo S40 (2004–2013)2011–2012Engine B4204S3 only · Transmission MPS6 only
- Volvo V50 (2004–2013)2008Engine D4204T only · Transmission MPS6 only
- Volvo V50 (2004–2013)2009–2010Engine B4204S3, D4204T only · Transmission MPS6 only
- Volvo V50 (2004–2013)2011–2012Engine B4204S3 only · Transmission MPS6 only
What does this fault code mean?
Shift fork 1 is jammed and stays put when the TCM asks for a shift. The cause may be a damaged shift fork, a damaged position sensor, or a lack of hydraulic pressure to the shifting system.
Possible causes
- Damaged shift fork
- Damaged position sensor
- No hydraulic pressure to the shifting system
What you can do
- 1Read out the fault codes from the transmission control module; if a code concerns hydraulics or a position sensor, trace that one first
- 2With diagnostic equipment, run the control routine with the engine on, the parking brake applied and the selector in P, and listen for a clonking sound
- 3If several forks stay put, the fault is in the mechatronic unit, which a workshop should replace
- 4If only the position sensor for shift fork 1 misses its position but the clonking sound is heard, the sensor is at fault
- 5If there is no clonking sound and the sensor does not move as required, a mechanical fault in the transmission is likely; a workshop should check it
- 6Have a workshop check that the control module has the latest software before the car is returned
Symptoms you may notice5
- Check engine light comes on or behaves abnormally
- Text window with yellow warning symbol and message
- No forward or reverse movement with a gear selected
- Shifts occur too early, too late or too often, sometimes or all the time
- Gears shift hard or jerky, sometimes or all the time
General guidance for car owners. Diagnosis on the car can point to a different cause.