Code result
P27B5
Internal Control Module Transmission Gear Ratio Control Performance
High severity
What it means
The internal gear ratio control logic in the transmission control module does not produce the expected commands.
Is it safe to drive?
No — stop driving
This code points to a problem that can cause damage or affect safety. Avoid driving and have the vehicle diagnosed promptly.
Most likely causes
Internal software logic fault
highOne of the most commonly reported causes for this code — check this first.
Memory corruption in TCM
mediumA plausible cause — test and verify before replacing parts.
Related help
Get the full diagnosis
Add your vehicle and see step-by-step repair help, recalls, and TSBs in Wrenchify.
Diagnose P27B5 freeNo credit card required