OBD-II code · Powertrain (generic, extended)
P27B4 Internal Control Module Transmission Gear Direction Control Performance
The internal gear-direction control logic in the transmission control module does not produce the expected commands.
Is it safe to drive with P27B4?
Usually safe for short trips, but don’t ignore it: the underlying fault can get more expensive over time.
Common causes
- Most likelyInternal software logic fault
- PossibleMemory corruption in TCM
Symptoms
- Check engine or transmission warning light on
- Harsh, delayed, or missing shifts
- Possible limp mode (locked in one gear)
- Slipping or shuddering during gear changes
Repair at a glance
- Difficulty
- Hard
- DIY friendly
- Best left to a mechanic
- Typical labour
- 1–4 h
- Emissions test
- Usually unaffected
- Parts involved
- Tcm
Related codes
- P27B1Internal Control Module Transmission Range Select Performance
- P27B2Internal Control Module Transmission Range Control Performance
- P27B3Internal Control Module Transmission Gear Select Performance
- P27B5Internal Control Module Transmission Gear Ratio Control Performance
- P27B6Internal Control Module Transmission Speed Sensor Performance
- P27B9Pressure Control Solenoid N Performance/Stuck Off
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.