P0606: ECM/PCM Processor Fault
Key takeaways
- P0606 means a control module, usually the engine computer, found a problem with its own processor or memory during an internal self-check.
- Drive short trips only: the car may go into reduced power or stall; if it stalls or won't accelerate, have it towed.
- Check for a software update first, then battery voltage and grounds; the module itself should be the last thing replaced.
- 161 manufacturer bulletins from 23 makes name P0606, and several GM bulletins cover it set in the body or lighting module rather than the engine computer.
- A replacement engine computer runs $800–$1,800 plus programming, so rule out the cheaper causes first.
What P0606 means
Your engine computer checked itself and didn’t like the answer. Scanners call it “ECM/PCM Processor Fault” or, on some makes, “Control Module Processor Performance.” Engine computers run constant internal tests: they compare the results of two processors, check their memory, and watch that the software keeps running on schedule. When one of those tests fails, the module stores P0606.
The code doesn’t always mean the chip is broken. Software bugs, low or unstable supply voltage, a bad ground and water in the connector can all make a healthy module fail its self-test. And on some newer cars a module other than the engine computer, such as the body or lighting module, can set P0606 and light the check engine light.
Is it safe to drive?
Short trips only. Because the computer can’t trust its own processing, it may cut power to a reduced-power mode, limit throttle, shift oddly or, in the worst case, stall. That’s why P0606 rates high even when the car seems normal.
The answer becomes no if the car stalls, won’t accelerate, or the throttle doesn’t respond properly. A stall at speed takes away power steering and brake assist; have it towed instead. If it drives normally, keep trips short and local until it’s checked. See can I drive with the check engine light on for the general rules.
Causes, ranked
| Cause | How you confirm it | Typical cost (US independent shop, 2026) |
|---|---|---|
| Engine computer software needing an update | A bulletin covers your make, model and year; shop checks the software level | $100–$200 |
| Low or unstable voltage (weak battery, charging fault) | Battery and charging test; P0562 or P0563 stored too | $150–$350 for a battery |
| Loose or corroded battery terminals or engine computer grounds | Voltage drop test at the grounds and at the module connector | $20–$120 |
| Water, corrosion or bent pins in the engine computer connector | Inspect the connector and harness near the module | $100–$250 |
| A different module setting the code (body or lighting module) | Full-vehicle scan shows which module stored P0606 | $100–$200 if software; more if that module is replaced |
| Failed engine computer | Updates, power, ground and connector all good; code returns | $800–$1,800 plus programming |
What to check first
- Scan every module, not just the engine. Find out which module stored P0606 and what other codes came with it.
- Check for a software update or bulletin. This comes before any part. The bulletins show a clear pattern: GM covers P0606 set in the lighting control module on 2024 Silverado and Sierra heavy-duty trucks and in the body control module on 2020–2023 Buick, Cadillac and Chevrolet models, plus a 2024 Traverse and Acadia repair and a heavy-duty Silverado and Sierra condition where P0606 comes with voltage codes. Subaru has a bulletin on how the code is set on its 2.0L and 2.4L turbo engines.
- Test the battery and charging system. A healthy battery rests near 12.6 volts, running voltage around 13.5 to 14.7.
- Clean and tighten the terminals and engine computer grounds, and check the module connector for water or corrosion.
- Clear it once and see if it returns. A one-time P0606 after a jump start or battery change may not come back.
- Replace the module last, and only a unit programmed to your car’s VIN.
35 owner complaints filed with NHTSA mention P0606. The Ford Fiesta leads with 6, four of them 2016 models, and the Ford Focus and Chevrolet Silverado 1500 have 4 each. These are owner reports, not confirmed defects.
What it costs
The cheap outcome is cleaned terminals or a tightened ground, $20–$120. The common outcome is a software update at $100–$200, or a battery at $150–$350. The expensive outcome is a replacement engine computer at $800–$1,800 plus programming. A $100–$180 diagnosis that checks software and voltage first is how you avoid buying a module that didn’t need replacing.
Related codes
P0606 often appears with P0562 or P0563 (system voltage low or high), which point to the battery or charging system first. P0605 and P0607 are sibling internal-module faults for memory and control module performance. Other modules may log U0401 when the engine computer’s data can’t be trusted.
What owners report to NHTSA
35 complaints filed with NHTSA mention P0606, 24 of them since 2015, across 22 different models. The component owners most often filed it under: electrical system.
Most-reported models
| Vehicle | Complaints | Model years reported |
|---|---|---|
| FORD FIESTA | 6 | 2011, 2012, 2016 |
| FORD FOCUS | 4 | 2012, 2014 |
| CHEVROLET SILVERADO 1500 | 4 | 2019 |
Manufacturer service bulletins that name P0606
161 technical service bulletins and manufacturer communications filed with NHTSA mention P0606, from 23 makes. A bulletin means the manufacturer has documented a known cause or a fix procedure for that model. Examples:
- SUBARU SUBARU, bulletin 10233913: This Bulletin provides information regarding DTC P0606 related specifically to the determination of this code on models equipped with 2.0L & 2.4L Turbo Engines.
- CHEVROLET SILVERADO 3500 (2024), bulletin 10249462: This technical bulletin provides repair information to correct a customer concern of Headlamps Flashing and/or DTC P0606 Set in Lighting Control Module.
- GMC SIERRA 2500 (2024), bulletin 10249462: This technical bulletin provides repair information to correct a customer concern of Headlamps Flashing and/or DTC P0606 Set in Lighting Control Module.
- GMC SIERRA 3500 (2024), bulletin 10251916: This technical bulletin provides repair information to correct a customer concern of Silverado and Sierra Setting DTC P0606 and either DTC P0562 or P0563.
- CHEVROLET SILVERADO 2500 (2024), bulletin 10251916: This technical bulletin provides repair information to correct a customer concern of Silverado and Sierra Setting DTC P0606 and either DTC P0562 or P0563.
- CHEVROLET TRAVERSE (2024), bulletin 11004423: This technical bulletin provides repair information to correct a customer concern of MIL Set P0606: Control Module Processor Performance.
Sources: NHTSA Office of Defects Investigation complaint database and manufacturer communications file, snapshots September 2026. A complaint or bulletin that mentions a code is a report about that vehicle, not a statement that the code has one cause.
Frequently asked questions
Can P0606 be fixed without replacing the ECM?
Often, yes. Many P0606 cases are fixed by a software update, and others by a battery, a ground or a connector. Replace the engine computer only after a shop has checked for updates and confirmed good power and ground at the module.
Can a weak battery cause P0606?
It can. The computer's self-check depends on stable supply voltage, and GM bulletins cover P0606 setting together with the low- and high-voltage codes P0562 and P0563. If you see those codes too, fix the voltage problem first.
Can I clear P0606 and keep driving?
You can clear it once to see if it returns, especially after a jump start or battery work. If it comes back, or the car goes into reduced power, stalls or has throttle problems, get it checked before relying on it.
Which module set P0606?
Usually the engine computer, but not always. On some newer GM vehicles the body control module or lighting control module can set P0606 and turn on the check engine light. A shop scan of all modules shows which one stored it, which changes the repair completely.