P0602: Control Module Programming Error

What it means

The control module detected a programming error. The code does not by itself establish that the module is missing calibration data or was recently replaced.

At a glance

• Usually lights the check-engine light

How it works

A control module needs valid programming data to operate its vehicle-specific functions. P0602 sets when the module detects a programming error, which may follow an incomplete flash or installation of a replacement module that has not been correctly coded.

Common causes

Most likely first.

1. Replacement ECU not coded to vehicle
2. Partial / interrupted flash

Symptoms

• Check engine light on
• Possible limp mode or no-start
• Multiple follow-up faults across modules
• Reset/relearn may be needed after repair

How to diagnose it

1. Save freeze-frame data and scan all modules for programming, configuration, and communication faults before clearing codes.
2. Check repair history for a recent module replacement or interrupted programming attempt.
3. Verify that the installed module is the correct application for the vehicle and that its connectors and power and ground circuits are secure.
4. Use the manufacturer's service information to check the module's coding and calibration status and for a required update.
5. If programming status is correct but P0602 returns, test module power and ground during operation and assess the module for an internal fault.

Common fixes

• Correct a poor module power, ground, or connector connection that could interrupt programming.
• Complete the manufacturer's programming procedure if a flash was interrupted.
• Code or configure a replacement module for the vehicle.
• Replace the module if it cannot retain or accept correct programming.

Can I keep driving?

If the vehicle starts and drives normally with a steady warning light, keep trips short and avoid situations where limp mode or a no-start would be hazardous. Stop driving if power becomes restricted or the engine stalls.