OBD-II Code · Computer
P0605
PCM ROM 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 read-only memory fault.
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
Likely causes
- Failed PCM
Read the full diagnostic procedureP0605 indicates an internal ROM (read-only memory) fault inside the PCM — the chip holding the engine-control program code itself has failed its chec…
P0605 indicates an internal ROM (read-only memory) fault inside the PCM — the chip holding the engine-control program code itself has failed its checksum or readback test. This is a hard processor-side failure on virtually every platform; ROM is not user-serviceable and cannot be repaired by reflashing in most cases because the flash controller or memory die has physically failed.
Still, do the cheap verifications first
- confirm battery voltage 12.4V+ at rest, check all PCM grounds for under 0.1V drop, inspect for water intrusion at the PCM mounting location, and attempt a J2534 reflash with the latest OEM calibration.
- On a small percentage of vehicles a failed prior flash left the ROM in a recoverable state and a fresh reflash with a properly regulated power supply (13.5V minimum throughout) brings the module back.
- If the module will not communicate, will not accept a flash, or returns P0605 immediately after a successful flash, the PCM is dead.
- The expensive misdiagnosis is paying for repeated reflash attempts at a dealer when the module is hardware-failed; once two reflash attempts with proper voltage have failed, stop spending money on programming labor and replace the module.
Vehicle-specific patterns2003-2007 GM trucks and SUVs with the E40 PCM and 2007-2013 vehicles with the E38/E67 are the most common P0605 candidates, almost always requiring r…
- 2003-2007GM trucks and SUVs with the E40 PCM and 2007-2013 vehicles with the E38/E67 are the most common P0605 candidates, almost always requiring replacement and SPS reprogramming with VIN configuration.
- 2003-2010Ford F-Series with the Copperhead and later PCMs throw P0605 from heat-soaked or water-damaged modules mounted on the firewall, requiring replacement plus PATS relearn for immobilizer linkage.
- 2005-2010Chrysler/Dodge/Jeep with the NGC and later powertrain modules set P0605 from heat fatigue on solder joints near the main processor BGA, requiring replacement and wiTECH PIN-based reprogramming.
- 2003-2008VW/Audi with the Bosch ME7/ME9 ECU show equivalent ROM faults requiring replacement and immobilizer adaptation via ODIS.
Estimated repair$600 to $2,000.
Look up another code
P0605 — frequently asked
What does a P0605 code mean?
PCM read-only memory fault.
What causes a P0605 code?
Common causes: Failed PCM.
What are the symptoms of a P0605 code?
Typical symptoms: Check engine light.
Is it safe to drive with a P0605 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 P0605 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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