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P0602 Error Code: Causes, Symptoms, Diagnosis, and How to Fix It

  • Cars Explained
  • Natasha Young
  • 4 minutes

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The OBD-II code P0602 error code implies a Control Module Programming Error. This is one of the most common OBD2 error codes. Wondering how to fix this engine code? Read to know more. 

What is the P0602 error code? 

A P0602 code happens when the Engine Control Module (ECM) gets a message from the Powertrain Control Module (PCM) that an internal programming error has been recognized. The PCM has a problem. 

When the Powertrain Control Module stores a P0602 trouble code, it usually means that there is a programming error in one of the control modules, such as:

  • Transmission control module
  • The anti-lock brake control module
  • Anti-theft module
  • Body control module
  • Climate control module
  • Cruise control module
  • Fuel injection control module
  • Instrument panel control module
  • Proximity alert module
  • Traction control module
  • Turbo control module

p0602 error code

P0602 error code: Symptoms 

Error code P0602 needs to be rectified sooner as the conditions that caused it to be stored will undoubtedly have a significant impact on engine management. Such as:

  • Hard or no start condition 
  • Reduction in fuel efficiency 
  • Stalls or rough idling of the engine 
  • Transmission shifting that is harsh or erratic 

P0602 error code: Causes 

The three most likely reasons for error code P0602 are a poor electrical connection, a programming error, or a faulty PCM driver. Additional potential causes include: 

  • Faulty, rusted, or broken CAN connections or wirings 
  • Faulty grounding cable or module ground strap 
  • Malfunctioning CAN bus 
  • New or improper PCM 
  • Installed aftermarket (high-performance) PCM programme 
  • Melted PCM fuse 
  • Bad relay for PCM power supply 
  • CAN harness with open or shorted wiring or connectors 

P0602 error code: Diagnosis 

Inspect the system for any loose connections or damage. Examine all wiring, connectors, and components for any damaged or loose connections.

You will be able to retrieve all frozen frame data and recorded error codes. This information could be relevant when determining the order in which trouble codes were logged. First, clear the code, then drive the vehicle to determine if the problem persists. 

If the error code persists, use a specialist scanner to determine the cause of the code storage more rapidly. If testing is not performed properly, it can also be time-consuming and expensive for the mechanic. When testing if a vehicle’s circuits are in gear, you will get accurate results. 

In the event that a probe is misplaced, it is recommended to install a memory-saving device or risk having to reprogram the PCM and other control modules. 

Using the digital volt/ohmmeter, test the continuity and ground of the batteries for all control modules. Using a wiring diagram, examine the continuity between the control modules in a CAN Bus system. Finally, clear the code and see whether it returns. 

Mistakes while diagnosing P0602

Mistaking other trouble codes, such as those involving engine misfires, lean exhaust, or the fuel injector, as the cause of the error code in the vehicle is one of the most frequent errors made when diagnosing a P0602 issue code.

If you do not correctly diagnose the problem, it may fail, and the error code may return. By fixing the broken component and clearing the diagnostic issue codes stored in the PCM, a misdiagnosis can be prevented.  

How serious is P0602? 

In addition to affecting vehicle performance, such as acceleration, shifting, and idling, a P0602 trouble code can also influence fuel economy, hence reducing the vehicle’s efficiency. Therefore, it can be considered serious in the long run, especially if ignored for a long time.

What are the fixes for the P0602 error code? 

The precise repair steps may vary depending on the model year, manufacturer, and powertrain configuration. 

  • Replace any broken or malfunctioning connectors, components, or wiring, and ensure that all connectors are firmly fastened. 
  • Replacement of defective components in certain control modules 
  • Changing a defective PCM 

This error code is frequently confused with codes referring to engine misfire, low exhaust, or fuel injector, resulting in incorrect diagnosis and ineffective repair. In addition to the poor acceleration, shifting, and idling performance, error code P0602 can adversely influence the fuel economy of the vehicle, making it less fuel efficient. 

How much does it cost to fix P0602

The cost to fix a P0602 code varies based on the kind and extent of the damage. Some professionals may charge a fixed cost ranging from $100 to $300, while others prefer invoicing based on time and materials utilized. Other elements include: 

  • Some control modules might cost between $500 and $1,000. 
  • The average hourly wage in your location may be between $75 and $120. 


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