Is P0606 always a PCM failure?

Not always. Check battery voltage, ground connections, and TSBs for your model before replacing the PCM. Some cases are electrical, not hardware.

How much does a replacement PCM cost?

The PCM part itself runs $200 to $800 depending on the vehicle. Programming adds $80 to $200. Total with labor is often $500 to $1,500.

Can I buy a used PCM?

Sometimes, but used PCMs must be programmed to your specific VIN. Not all used modules can be reprogrammed. Confirm with your shop before buying one.

Codes › P0606

P0606: The engine computer processor has a fault

PCM Processor Fault

SevereCan you keep driving?

Do not drive if there are symptoms like no-start, stalling, or loss of control over engine or transmission functions. Have it towed if necessary.

What it means

P0606 means the PCM detected a fault in its own internal processor during a self-diagnostic check. The processor is the calculating core of the engine computer. Unlike P0601, which is a memory error, P0606 is a processing fault. This often means the PCM itself has failed and needs replacement or reprogramming. However, low battery voltage, ground faults, and certain wiring issues can force false processor faults by starving the PCM of the stable power it needs to run correctly. Always verify the electrical system before replacing the PCM.

Common causes

Internal PCM processor failureThe processing chip inside the PCM has failed. Requires replacement.
Unstable or low supply voltage to the PCMPCMs require stable voltage. A failing battery or loose ground can cause processor faults.
Bad PCM ground connectionA corroded or loose PCM ground strap is a common trigger, especially on older vehicles.
Software corruption requiring reflashOn some models, a manufacturer reflash resolves the fault without hardware replacement.

What it costs

PCM reflash or reprogramming$80 to $200
PCM replacement and programming$500 to $1,500

Symptoms

Check engine light on
Multiple systems may malfunction simultaneously
Erratic engine behavior
Possible no-start
Other codes stored alongside P0606

What to do next

Check all PCM power and ground connections first. Inspect the main PCM ground strap where it attaches to the chassis or engine block for corrosion. Verify battery voltage is within spec. If the electrical system is sound, bring the vehicle to a dealer or independent shop with factory diagnostic tools. Check if a technical service bulletin exists for P0606 on your model before authorizing PCM replacement.

Lewis captures all stored codes at the time of the scan, which helps establish whether P0606 appeared alongside an electrical event or as a standalone processor failure. Download Lewis.

Related codes

FAQ

Is P0606 always a PCM failure?: Not always. Check battery voltage, ground connections, and TSBs for your model before replacing the PCM. Some cases are electrical, not hardware.
How much does a replacement PCM cost?: The PCM part itself runs $200 to $800 depending on the vehicle. Programming adds $80 to $200. Total with labor is often $500 to $1,500.
Can I buy a used PCM?: Sometimes, but used PCMs must be programmed to your specific VIN. Not all used modules can be reprogrammed. Confirm with your shop before buying one.