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P0601 – What Does It Mean and How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.

Definition

P0601 is an OBD-II Code that refers to Internal Control Module Memory Checksum Error

Meaning

A P0601 code is a general diagnostic trouble code that occurs when the ECM/PCM detects an internal error in the program memory. The PCM's memory checksum test is conducted on a regular basis. Because all of the short-term operational calculations and operating system software are saved in the memory, it ensures the PCM's trustworthiness and may not work properly if this part of its functionality has issues.

Causes

Common causes for this code include:

  • Malfunctioning Power Control Module (PCM) 
  • Open or shorted PCM harness
  • Poor electrical connection PCM circuit 
  • Low battery voltage is low

Symptoms

The symptoms of a P0601 code are:

  • Illuminated Check Engine Light
  • Illuminated ABS and traction control lights 
  • No-start condition may be exhibited
  • The vehicle may randomly loose power or stop working
  • The transmission may not shift appropriately

Diagnosis

To diagnose a P0601 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Visually inspect all related wiring and connectors.
  3. Check for any loose, damaged or corroded wiring or connectors.
  4. Use a test light or multimeter to check connections and circuits for power and ground.
  5. If the harness and connectors are all in good condition, replace the PCM.

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P0601 code:

  • Not thoroughly inspecting all the wiring and connectors for damage.
  • Not checking the PCM for corrosion.
  • Replacing only the ECM when the problem is actually with the TCM or another module.

How serious is this?

A P0601 code is a serious malfunction, as it can cause multiple parts of the vehicle to stop working. Because the code can result in a no-start condition, it should be addressed as soon as possible.

What repairs can fix the code?

The following are solutions that may fix this problem:

  • Broken or faulty wirings must be repaired or replaced
  • A new power control module must be installed
  • A new ECM/PCM may need to be flashed or programmed

Related codes

A P0601 is related to and may be accompanied by the following codes:

P0602 – Internal Control Module Random Access Memory Error

P0603 – Internal Control Module Keep Alive Memory Error

P0604 – Internal Control Module Read Only Memory Error

P0605 – Internal Control Module ROM Checksum Error

Conclusion

In conclusion, the P0601 code is a diagnostic trouble code that refers to a problem with the internal control module's memory. The common causes for this code are a malfunctioning power control module or a short in the PCM harness. Symptoms of this code include the check engine light being illuminated, the ABS and traction control lights being illuminated, and the transmission not shifting properly. 

To diagnose this code, a technician would scan for codes in the ECM and look at the freeze frame data for failure. They would then visually inspect all related wiring and connectors. If the harness and connectors are all in good condition, they would replace the PCM. Some common mistakes that technicians make when diagnosing this code include not thoroughly inspecting all the wiring and connectors for damage and not checking the PCM for corrosion. A P0601 code is a serious malfunction and should be addressed as soon as possible.