OBD-II Code · Computer
P0601
Internal Control Module Memory Check Sum Error
Severity
high
Left alone, this one tends to take other parts with it.
Can you drive it
Only if running normally
A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety.
Indicative cost (USD)
$400–$1,500
Varies by vehicle, diagnosis, parts, and local labor. This is not a repair quote.
PCM internal memory failure.
How a shop works this
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed.
Note every code that is set, not just this one.
Codes that appear together usually narrow the cause faster than any one of them read alone.
Read the freeze frame — the conditions the fault was recorded under.
Cold or warm, idle or load, road speed and engine speed. A fault that only appears cold is a different fault from one that only appears under load, even with the same code on the scanner.
Confirm the fault is current rather than history.
Clear the code and see whether it returns under those same conditions. A code that does not come back may have been logged during a repair, a flat battery, or a bad connection that has since been disturbed.
Then work the likely-causes list in the order shown.
That order is what a shop checks first for this code — wiring and connections before the component they run to, because a connector costs nothing to inspect and is a common answer.
If the code comes back after a repair, the underlying fault is still there. That is the point to bring in a scanner with live data and freeze-frame, or a shop that has one.
Common symptoms
- Check engine light
- Erratic behavior
Likely causes
- Failed PCMMost common
- Low battery during reflash
Read the full diagnostic procedureP0601 means the PCM has run its internal checksum on flash memory and the calculated value does not match the stored value, indicating either corrupt…
P0601 means the PCM has run its internal checksum on flash memory and the calculated value does not match the stored value, indicating either corrupted flash or a hardware failure in the memory chip itself. Before condemning the module, confirm battery voltage is solid (12.4V+ at rest, no more than 0.5V drop during accessory load) because low or unstable voltage during a prior reflash attempt is a leading cause of corrupted checksums. Check all PCM grounds for under 0.1V drop relative to battery negative under load, and inspect the PCM connector and case for water staining, green corrosion, or the telltale white crust of dried coolant — water intrusion at the PCM (commonly mounted low on the firewall, in the kick panel, or under the cowl) is the dominant root cause on older GM and Ford applications. Try a J2534 reflash with the latest OEM calibration before ordering a module; on many platforms a successful reflash clears P0601 permanently because the flash cells were merely written incorrectly, not physically failed. The expensive misdiagnosis is buying a remanufactured PCM, having it programmed and VIN-married, then discovering the cowl drain is still leaking onto the new module — fix the water source first or you will buy the same PCM twice.
Vehicle-specific patterns1999-2004 Ford F-150, Expedition, and Mustang with the PCM mounted on the passenger-side firewall develop P0601 from cowl leaks soaking the connector…
- 1999-2004Ford F-150, Expedition, and Mustang with the PCM mounted on the passenger-side firewall develop P0601 from cowl leaks soaking the connector, with TSB 06-7-13 documenting the water-intrusion pattern.
- 2003-2007GM trucks and SUVs (Silverado, Tahoe, Trailblazer) running the 5.3L or 4.2L I6 frequently set P0601 from internal E40/E67 PCM flash failure, and GM bulletin 05-06-04-035 covers reprogramming as the first step before replacement.
- 2001-2006Chrysler/Dodge minivans and the 2005-2010 300/Charger throw P0601 from heat-soaked SBEC/NGC modules mounted near the battery.
- 2002-2008BMW E46/E60 with the MSV70/MSV80 DME throw equivalent internal-checksum faults from cracked solder joints on the flash IC, a known soldering-defect pattern.
Estimated repair$80 to $1,600.
Look up another code
P0601 — frequently asked
What does a P0601 code mean?
PCM internal memory failure.
What causes a P0601 code?
Common causes: Failed PCM; Low battery during reflash.
What are the symptoms of a P0601 code?
Typical symptoms: Check engine light; Erratic behavior.
Is it safe to drive with a P0601 code?
Only if running normally. A short trip to a shop may be reasonable if the light is steady and the car runs normally. Stop safely for a flashing light, severe shaking, overheating, loss of power, or another urgent warning. The code alone cannot confirm safety. Estimated repair: $400-$1,500.
How do I diagnose a P0601 code?
Work from evidence to part, not the other way round. A code names a circuit or a symptom; it does not name the part that failed. 1. Note every code that is set, not just this one. 2. Read the freeze frame — the conditions the fault was recorded under. 3. Confirm the fault is current rather than history. 4. Then work the likely-causes list in the order shown.
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