P27B4

Internal Control Module Transmission Gear Direction Control Performance

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$56–278 (est.)

Symptoms

Incorrect gear shifting
Car won't shift into certain gears
Delays when shifting gears
Transmission transition to emergency mode
Check Engine light comes on

Causes

Transmission control module (TCM) malfunction
Problems with shift solenoids
Open or short circuit in wiring harness
Low or contaminated transmission fluid
Mechanical damage inside the transmission

How to Fix

Check the level and condition of the transmission fluid
Diagnose the transmission control module
Check the condition of the gearshift solenoids
Inspect the wiring harness for damage
If necessary, replace the transmission control module

Related codes

P27B5 P27B6 P27B7