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P0601 OBD-II Trouble Code: Internal Control Module Memory Check Sum Error

Check Engine Light

P0601 code definition

P0601 is a general OBD-II trouble code referencing a fault with the internal control memory. This code may be seen with other ECU codes and various other codes depending on the symptoms.

What the P0601 code means

The P0601 diagnostic trouble code is set when a memory check sum error is detected with the internal control module. This is a error internal to the ECU and is found when the ECU performs self-checks. P0601 then causes the Check Engine Light to illuminate and failsafe mode to become enabled until normal operation resumes or the code is repaired.

What causes the P0601 code?

The most common causes of the P0601 code are:

  • ECU failing or has failed
  • Low voltage to the ECU

What are the symptoms of the P0601 code?

Symptoms can vary greatly with ECU codes and some symptoms can be very erratic and intermittent such as:

  • Check Engine Light illuminated on the dashboard
  • ABS and traction control systems lights are on
  • Vehicle may not shift properly
  • The vehicle may struggle to stay running or die while running
  • Engine may not start

How does a mechanic diagnose the P0601 code?

  • A mechanic will begin by hooking up a scan tool to the DLC port and checking for all codes preset including history and pending code.

  • Next, freeze frame data will be noted for every code. This information is critical as it tells us what conditions, such as RPM, engine load, and coolant temperature the vehicle was under when the code was set.

  • All codes will then be cleared and taken on a test drive to confirm any issues found, the test drive should be under similar circumstances to when the code was set.

  • Next, a visual inspection will be performed to look for any damaged wiring or circuits.

  • Then, a multimeter will be used to check for proper voltage supply going to the ECU.

  • Lastly, the ECU will need to be tested. Each vehicle has its own testing procedures for the ECU.

Common mistakes when diagnosing the P0601 code

The most common mistake is not checking that the ECU is receiving proper voltage, the ECU then tests bad and is replaced when it is not the cause. All steps must be followed as P0601 can be a difficult code to diagnose with intermittent issues.

How serious is the P0601 code?

The seriousness of P0601 varies greatly with the symptoms. The vehicle should not be driven when it has extreme drivability faults or is struggling to stay running.

What repairs can fix the P0601 code?

  • Restoring proper voltage to the ECU
  • ECU replacement

Additional comments for consideration regarding the P0601 code

When the ECU has low voltage, it causes the same erratic symptoms as a failing ECU. If a battery was installed backwards or the main fuse was partially blown, the voltage supply to the engine control module may be much lower than it should be.

An advanced level scan tool is a necessity when diagnosing the P0601 code. These scan tools are used to monitor the ECU operation and can graph fluctuations in voltage allowing intermittent issues to be found.

Need help with a P0601 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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