What Does P0602 Mean?
P0602 indicates that the ECM/PCM has detected a programming error in its Read-Only Memory (ROM). The module has determined that the calibration or software stored in ROM does not match the expected configuration for the vehicle. This commonly occurs after a failed reprogramming attempt, an incorrect calibration file, or internal hardware failure. The driver may experience check engine light, limp mode, or poor drivability.
Safety Warning
Do not drive. Incorrect or corrupted ROM programming means the ECM may not properly control fuel injection, ignition timing, emission systems, or transmission operation. The vehicle could stall, run dangerously lean or rich, or fail to shift properly. Tow to a dealership or qualified repair facility with reprogramming capability.
Common Causes
35%
Incomplete or interrupted ECM/PCM reprogramming (flash update)
25%
Wrong calibration file loaded into the ECM/PCM for the vehicle application
20%
Internal ECM/PCM hardware failure causing ROM read errors
15%
Power interruption during ECM operation causing partial ROM corruption
5%
Aftermarket ECM or refurbished module with incompatible firmware
Diagnostic Steps
1
Verify the ECM/PCM part number and calibration ID match the correct application for the vehicle's VIN, model year, engine, and transmission using manufacturer service information.
2
Attempt to reprogram the ECM/PCM with the correct and latest calibration file from the manufacturer. Ensure the battery is fully charged (12.6V+) and connected to a charger during the process.
3
Check for Technical Service Bulletins that address P0602 for the specific vehicle — many manufacturers have issued updated calibration files that resolve this code.
4
If reprogramming fails or the code returns immediately, test ECM power supply stability during the flash process using a voltmeter — voltage must remain above 11V throughout.
5
If the ECM cannot be successfully reprogrammed, replace with a new OEM module and program it to the vehicle's VIN with the correct calibration.
Estimated Repair Cost
$150 - $1,600
Parts + labor, varies by vehicle and location
P0602 indicates that the ECM/PCM has detected a programming error in its Read-Only Memory (ROM). The module has determined that the calibration or software stored in ROM does not match the expected configuration for the vehicle. This commonly occurs after a failed reprogramming attempt, an incorrect...
The most common cause of P0602 (Control Module Read Only Memory(ROM)) is: Incomplete or interrupted ECM/PCM reprogramming (flash update)
Typical repair costs for P0602 range from $150 to $1,600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Do not drive. Incorrect or corrupted ROM programming means the ECM may not properly control fuel injection, ignition timing, emission systems, or transmission operation. The vehicle could stall, run dangerously lean or rich, or fail to shift properly. Tow to a dealership or qualified repair facility with reprogramming capability.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P0602 to identify the root cause.
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Quick Info
Category
Powertrain
System
Engine Control Module
Difficulty
Type
Generic (SAE)
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