Internal Control Module Memory Check Sum Error
The P0601 code means the vehicle's onboard diagnostic system has detected: Internal Control Module Memory Check Sum Error. This is a critical severity code.
- Keep driving?
- Short distances only
- DIY difficulty
- hard
- Estimated cost
- $100 - $1200 (parts and labor)
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Common Symptoms
- Check Engine Light illuminated
- Engine may run rough or stall
- Multiple system malfunctions
- Vehicle may not start
- Erratic gauge behavior
Probable Causes (Ranked by Likelihood)
- Corrupted ECM/PCM internal memory Very High
- Failed ECM/PCM reprogramming attempt High
- Electrical spike or voltage surge damaging ECM memory Moderate
- Defective ECM/PCM hardware Moderate
Common Fixes by Vehicle
What techs usually find when diagnosing P0601 on specific vehicles — tap your vehicle for the fix and the exact part:
1999-2007 Chevrolet Silverado/GMC Sierra 5.3L Moderate DIY
PCM internal memory checksum error on GM trucks is often caused by low battery voltage during a cold start. Fully charge the battery and clear the code. If P0601 returns, the PCM needs to be replaced and reprogrammed. GM PCMs can be purchased pre-programmed with your VIN from aftermarket suppliers. Note: this module must be programmed to your VIN before the car will run. A generic parts search returns blank or donor units, so order it through a dealer or a rebuilder that programs to your VIN, or have a shop flash it after installation.
Labor: 1-2 hours2003-2011 Ford Crown Victoria/Mercury Grand Marquis 4.6L Moderate DIY
The PCM memory error on Ford 4.6L modular engines is sometimes caused by a poor ground connection at the PCM. The PCM grounds are on the firewall -- clean all ground terminals with a wire brush. If the code persists after clearing and driving, the PCM has an internal failure and must be replaced. Note: this module must be programmed to your VIN before the car will run. A generic parts search returns blank or donor units, so order it through a dealer or a rebuilder that programs to your VIN, or have a shop flash it after installation.
Labor: 1-2 hours2004-2013 Chevrolet Corvette/Camaro 6.0L/6.2L Moderate DIY
Water intrusion into the PCM housing causes memory errors on GM performance cars. The PCM is located in the engine bay and the connector seal deteriorates over time. Inspect the PCM housing for moisture. If wet, dry it thoroughly, replace the connector seal, and clear the code. Replace PCM if internal corrosion is found.
Labor: 1-2 hoursFrequently Asked Questions
Can I drive with code P0601?
Drive short distances only. Internal control module errors can cause unpredictable engine behavior.
Does P0601 mean I need a new ECM?
Not always. Some internal module errors can be resolved by reprogramming or reflashing the ECM with factory software. However, hardware failures (RAM, ROM, processor) typically require ECM replacement.
How much does an ECM replacement cost?
ECM replacement typically costs $300-$1500 including the part and programming. The ECM must be programmed with the correct calibration and vehicle options for your specific VIN.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Clear the code and recheck -- if it returns immediately, the ECM has a permanent fault
-
Check battery voltage and charging system -- low voltage can corrupt ECM memory
-
Verify ECM grounds are clean and tight
-
Attempt an ECM reflash or reprogramming with factory software
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Replace the ECM/PCM if reflashing does not resolve the checksum error
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P0601 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- 2003-2015 Honda Accord
- 2004-2016 Ford F-150
- 2005-2017 Chevrolet Silverado
- 2002-2014 Toyota Camry
Related Codes
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