Computer & output circuits · Powertrain · generic (SAE-defined)
P0606: Control Module Processor
P0606 means the engine computer's internal self-check found that its processor, or a monitoring processor inside the module, is not operating correctly.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0606 sets
Many powertrain control modules (PCMs) use two processors that cross-check each other, especially for electronic throttle control. If the processors disagree, a watchdog test fails, or the main processor reports an internal error, the PCM sets P0606. Because this is an internal integrity check, the setting logic is manufacturer-specific.
Common causes of P0606
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Internal PCM processor failure
- PCM software fault needing an update
- Low battery voltage or charging-system problems
- Poor PCM power or ground connections
- Corroded PCM connectors or water damage
- Faulty throttle-control circuit causing the cross-check to fail
P0606 symptoms
- Check engine light on
- Reduced power or limp mode
- Electronic throttle control warning light
- Stalling, hesitation or no-start
- Harsh or erratic shifting on some vehicles
How P0606 is diagnosed
- Record freeze frame data and all stored codes, especially throttle and network codes
- Check for service bulletins and software updates addressing P0606
- Test the battery, charging system and PCM power and ground circuits
- Inspect PCM connectors for corrosion, bent pins or moisture
- Inspect throttle body and pedal sensor wiring when throttle codes are also present
- Reflash the PCM, and replace it only if the fault persists with good power and wiring
Typical fixes for P0606
- Update the PCM software
- Repair grounds, power feeds or charging-system faults
- Repair throttle-control wiring if it is triggering the cross-check
- Replace the PCM and program it to the vehicle
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Manufacturer notes
Commonly reported on a range of vehicles with electronic throttle control, sometimes addressed by software updates; check factory service information and bulletins.
Related codes & warning lights
P0606 FAQ
What does code P0606 mean?
P0606 means the engine computer's internal self-check found that its processor, or a monitoring processor inside the module, is not operating correctly. The standard definition is "Control Module Processor."
Can I drive with a P0606 code?
Limit driving. Many vehicles respond to this fault with reduced power, and some may stall or lose throttle response unexpectedly, so have it checked as soon as possible.
Does P0606 always mean a new computer?
Not always. Software updates, battery and ground repairs, and throttle wiring repairs resolve some cases. Replacement is appropriate only after those are ruled out.
Why does P0606 often come with throttle codes?
The monitoring processor watches electronic throttle control closely. A throttle or pedal sensor problem can make the two processors disagree, which logs a processor fault along with throttle codes.
Keep researching
More computer & output circuits codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.