What does fault code TCM-0450 mean?

Diagnostic fault code details for TCM-0450 (Volvo C30 (2007–2013), Volvo C30 (2007–2013), Volvo C30 (2007–2013)). Repair service at OBD Tuning.

VOLVO

TCM-0450 - Gear change group, odd gears. Sensor indicates two gears engaged

System

Transmission Control Module (TCM)

Volvo models this fault code applies to

Applies to the following models:

4 models

C30 (2007–2013), C70 (2006–2013), S40 (2004–2013), V50 (2004–2013)

Show models by year and engine (10)

What does this fault code mean?

The transmission control module (TCM) has received a signal that two odd gears are engaged at the same time. The transmission has a mechanical interlock function that is meant to prevent this, so the fault is hard to trace. The position sensor or the interlock function may be damaged, but the fault often occurs together with a hydraulic fault.

Possible causes

Damaged position sensor
Interlock function damaged along with a hydraulic fault

What you can do

1Read out the fault codes from the transmission control module and deal first with any codes that may share the same cause
2Checking the sensor alone is not enough, because the fault often occurs together with a hydraulic fault
3Since the hydraulic fault may be inside or outside the mechatronic unit, the whole transmission has to be replaced; have a workshop do this

Symptoms you may notice5

Check engine light comes on or behaves abnormally
Text window with yellow warning symbol and message
Shifts occur too early, too late or too often, sometimes or all the time
No forward or reverse movement with a gear selected
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.