OBD-II code · Powertrain (generic, extended)
P27B5 Internal Control Module Transmission Gear Ratio Control Performance
The internal gear ratio control logic in the transmission control module does not produce the expected commands.
Is it safe to drive with P27B5?
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
- P27B2Internal Control Module Transmission Range Control Performance
- P27B3Internal Control Module Transmission Gear Select Performance
- P27B4Internal Control Module Transmission Gear Direction Control Performance
- P27B6Internal Control Module Transmission Speed Sensor Performance
- P27B9Pressure Control Solenoid N Performance/Stuck Off
- P27BAPressure Control Solenoid N Stuck On
Code data: OBDex open dataset (CC0). Labour times are typical ranges, not a quote.