P0606: Control Module Processor
The engine computer has detected a fault in its own processor during a self check.
What P0606 means
P0606 means the engine computer has found a problem with its own processor. RepairPal explains that the computer regularly performs routine calculations as a self check, and when the results are not what it expects, it sets P0606. Many computers have two processors that check each other, especially for electronic throttle control, and a disagreement between them can set this code. RepairPal lists symptoms including warning lights, poor shifting, lower fuel economy and dying at stops. KBB firmly advises against driving because the computer may not control the engine and transmission correctly. Causes include an internal failure, outdated or corrupted software, supply voltage or ground problems, and on some vehicles a fault in the electronic throttle system that the computer reports this way. Shops check charging voltage, power feeds and grounds first, then look for software updates and service bulletins. Many P0606 cases are fixed with a reflash. If the fault returns, the computer is replaced.
Common symptoms
- Check engine light on
- ABS or traction control light on
- Poor running, stalling at stops or misfire-like symptoms
- Harsh or incorrect shifting
- Decrease in fuel economy
Most common causes
- Internal engine computer failure
- Software that needs to be updated or reflashed
- Low system voltage or bad ground
- Faulty electronic throttle control on some vehicles
- Water damage or corrosion in the module
What to check yourself first
Have the battery and alternator tested. Check the battery cables and the engine to body ground straps for corrosion. Ask a dealer whether a software update or service bulletin covers P0606 on your vehicle.
Typical fixes and what they cost
| Fix | Typical cost | Note |
|---|---|---|
| Powertrain control system diagnosis | $61-$90 | Shops check for software updates, which fix P0606 on many vehicles. |
| Replace engine control module (ECM/PCM) | $1,122-$1,192 | If the processor fault returns after power, ground and software checks. |
| Replace throttle body | $623-$766 | On some vehicles P0606 is tied to electronic throttle control faults. |
| Replace alternator | $809-$1,088 | If low charging voltage is upsetting the computer. |
Typical US price ranges for parts and labor, not quotes. Your shop should confirm the cause with a diagnostic before replacing parts.
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Related codes
- P0601 Internal Control Module Memory Check Sum Error
- P0603 Internal Control Module Keep Alive Memory (KAM) Error
- P0604 Internal Control Module Random Access Memory (RAM) Error
- P2135 Throttle/Pedal Position Sensor/Switch "A"/"B" Voltage Correlation
- P0562 System Voltage Low