P27B5

Internal Control Module Transmission Gear Ratio Control Performance

Severity

🔴 High

Can you drive?

Do not drive — repair immediately

Approx. repair cost

$89–278 (est.)

Symptoms

Incorrect gear shifting
Jerks when switching
Transmission slipping
Switching to emergency mode
Check engine light comes on

Causes

Control module software failure
Module hardware failure
Damage to the wiring to the module
Module power problems
Contact corrosion

How to Fix

Diagnostics of the control module using a scanner
Checking the integrity of wiring and contacts
Checking module power and grounding
Module software update
Replacing the control module if necessary

Related codes

P27B6 P27B7 P27B4