P0601 Code: Meaning, Causes, + Diagnosis

P0601 is a somewhat rare OBD2 trouble code.  While it’s generic (it has the same meaning for all 1996+ model year vehicles), it’s most commonly found in vehicles made by Chrysler and GM (notably Chrysler).

While it indicates that the PCM’s memory failed a memory check, P0601 is commonly seen when people use OBD2 port plugin accessories on their vehicle.  These accessories are used to turn off cylinder deactivation technology, auto engine start/stop, and performance plugins.

P0601 Definition: Internal Control Module – Memory Checksum Error

P0601 Definition

The PCM (powertrain control module) has memory and a processor like any other computer.  The PCM’s processor performs a “checksum test” to verify the integrity of its onboard memory. 

If the PCM fails this self-diagnostic test, P0601 will be stored, and the check engine light will come on.

P0601 Symptoms

The symptoms associated with P0601 are wide-ranging if there are any at all.  Usually, there aren’t.  Here are the most common symptoms when they are present:

  • Check engine light– Other codes are likely to be present with P0601.
  • No start– The engine will have difficulty starting or won’t start at all.
  • Engine performance issues– The PCM controls the engine.  So the engine may stall or act erratically.

P0601 Causes and Diagnosis

P0601 Diagnosis

Here are the most common causes of P0601, as well as a proper order of diagnostic operations:

1. Reflashed PCM or OBD2 Dongle

If your computer was reflashed with a tune the manufacturer did not approve, that can cause P0601.

Those little dongles that plug into the OBD2 port that modify the way the vehicle runs or drives, they are notorious for causing P0601.  If you have one of these, pull it and reset the code.  If it doesn’t come back, you shouldn’t use the dongle anymore.

2. Bad PCM

Most of the time, with P0601, the only solution is to have the PCM replaced or reflashed, which means taking it to the dealer.


There’s not a lot you can do to clear P0601 at home.  The good news is that the PCM may be subject to the eight year 80,000 mile federal emissions warranty.  Here’s a link if you want to read more about that.

Good luck fixing your vehicle.