P0605 on 1999-2004 Jeep Grand Cherokee — Internal Control Module Read Only Memory (ROM) Error
1 vehicles · 1 makes · $300-$1,000 repair
How to diagnose and fix P0605: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Jeep Grand Cherokee · 1999–2004
The WJ PCM (engine computer) can develop internal faults — often heat/temperature-related micro-cracks or solder failures — that cause intermittent stalling, hard-to-diagnose no-starts and driveability problems that come and go with ambient temperature. A well-known WJ case: a 2000 4.7L stalled only when outside air exceeded ~60F; a rebuilt/replaced PCM cured it after many other parts were replaced in vain.
Common Symptoms
- Intermittent stalling, often correlated with heat/warm weather
- Crank but no-start that comes and goes
- Multiple unrelated sensor codes
- Driveability that improves when cold
- Repairs of individual sensors don't resolve it
How to Fix
Diagnose by elimination after CKP, fuel pump, and grounds are ruled out. Options: send the PCM for bench repair (specialists like Circuit Board Medics), or install a remanufactured PCM programmed to the vehicle's VIN and SKIM/immobilizer. Any replacement PCM must be VIN-programmed to run. Inspect PCM connectors/pins for corrosion first.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- UpFix repair-and-return service for the original WJ PCMOEMUpFix 46855
Bench repair of the vehicle's original PCM only after vehicle-side diagnosis confirms an internal module fault covered by the service Fitment/availability: SKU 46855 describes a repair-and-return service for 1996-2004 Grand Cherokee 4.0L…
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Sources for this issue (2)
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P0605 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0605 mean?
P0605 stands for "Internal Control Module Read Only Memory (ROM) Error." The module's internal Read Only Memory (ROM), which holds the operating program/calibration, failed its self-test. The stored program is corrupt or unreadable, an internal module hardware fault.
What are the most common causes of P0605?
The most common causes of P0605 are: Corrupted internal ROM/program memory, Failed or interrupted reprogramming, Low/unstable voltage during operation, Internal electronic component failure, Defective control module. The specific cause varies by vehicle.
How much does it cost to fix P0605?
Repair costs for P0605 range from $300 to $1,000, depending on the vehicle and root cause.
Which vehicles are affected by P0605?
Au7o has documented P0605 across 1 vehicle models from 1 manufacturers: Jeep.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.