Error Code P0601 is defined as Internal Control Module Memory Check Sum Error, meaning it’s a fault with the internal control memory. This code is a generic trouble code, meaning it applies to all vehicles equipped with the OBD-II system, especially vehicles made since 1996 up to present. It’s widely common among Chrysler and Dodge vehicles, though it can happen to almost all vehicle makes. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another.
This code means there’s an internal fault in the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes).
Depending on the symptoms, this code may be seen with other error codes as well.
Other Internal Control Module error codes include:
- Error Code P0602
- Error Code P0603
- Error Code P0604
- Error Code P0605
In many cases, the vehicle in question will likely not exhibit noticeable symptoms aside from the illumination of the Check Engine light. For other cases, symptoms usually include:
- ABS and Traction Control System light is activated
- The vehicle may not shift properly
- The engine may not start
- Vehicle struggles to stay running or die while idling
The two most common causes for this code are:
- Low voltage to PCM (possibly caused by short-circuiting inside, disconnected connectors or wires from PCM to battery, while the battery is still connected)
- Failing PCM
How to Check
Mechanics start their diagnosis of this code by hooking up a scan tool to the DLC port and checking for all codes present within the system, including history and pending code.
Next, they record the freeze frame data for every code. This information can be useful, as it tells the condition of the vehicle when the code was set, such as engine load, RPM, and coolant temperature.
Next, codes must be cleared, and vehicle must be taken for a test drive under similar conditions when the code was set, to determine if the code comes back.
If the code comes back, the mechanics will have to check the wirings and circuits for any damages.
The multimeter will be used to check for proper voltage supply going to the PCM.
The PCM must be tested. Thus, it’s best to consult with your vehicle’s service manual or take the vehicle to a trusted shop, as each vehicle has its own unique and specific testing procedures for its PCM.
How to Fix
The most common fix for this code is replacement or reprogramming of the PCM. In some cases, dealers can reflash the PCM and get it up and working. But in most cases, this problem requires replacement or reprogramming. Thus, the vehicle must be taken to its dealership.
Fortunately, in many cases, this replacement is covered by emission warranty.
The most common misdiagnosis for this code is not checking if the PCM is receiving the proper voltage, resulting to unnecessary replacement of PCM.
The severity of this condition varies depending on its symptoms. If the vehicle is struggling to run, then it must not be driven until the code is fixed.