P0606: ECM/PCM processor fault
The engine ECU detects a fault in its own processor. Sometimes the power supply or an earth is to blame, but often it is the unit itself.
| Code | P0606 |
|---|---|
| System | Engine and transmission |
| Group | P06xx, Control unit and auxiliary outputs |
| Type | Generic: it means the same on every make |
| Can you keep driving? | With care |
What P0606 means
The ECU contains a processor that does all the engine calculations, and it monitors itself. This code means it has spotted an error in that processor or in its internal operation. Before replacing it, rule out the battery, earths and any available software updates.
Most common causes
- Low battery or loose terminals
- Poor ECU earth or supply
- Water or corrosion in the ECU plug
- Software that needs updating
- Internal ECU fault
Symptoms
- Engine warning light on
- Limp mode, poor throttle response
- Jerking, stalling or hard starting
- Harsh automatic gear changes
Can you drive with P0606?
With care It may limit power or leave you stranded without warning. Drive carefully and get the car to a garage as soon as possible.
How to check it
Check the battery voltage on the scan tool with the engine off and running, and inspect terminals and earths. Ask the garage whether there is a software update, as on some cars this code is fixed that way.
How to read and clear P0606 with Final OBD
Plug an OBD2 scanner in under the steering wheel, switch the ignition on and open Final OBD. Under Faults you’ll see P0606 with this same explanation and whether it’s confirmed, pending or permanent.
With Free you read this code with its short description for nothing, and clear it if the engine stores it over standard OBD. With Pro you get the full explanation, how the car was running when it was logged (revs, temperature, load) and clearing in every control unit.
Clearing the code only turns the light off: if the cause is still there, it comes back. Clear it once it’s fixed, and not right before the ITV. It’s all in how to read and clear fault codes and in the ITV and OBD.
Similar codes
- P0602 Control module programming error
- P0603 Internal control module keep alive memory (KAM) error
- P0604 Internal control module random access memory (RAM) error
- P0605 Internal control module read only memory (ROM) error
- P0607 Control module performance
- P0615 Starter relay: circuit fault
- P0616 Starter relay: circuit low
- P0617 Starter relay: circuit high
- P0600 Serial communication link fault
- P0601 Internal control module memory checksum error
- P0620 Generator control: circuit fault
- P0621 Generator lamp L control: circuit fault
P0606 is a generic code, so it means the same on any make, for example on Alfa Romeo, Dacia, Kia, Nissan, Opel / Vauxhall, Škoda. See what Final OBD does on your car in makes and models.
What does code P0606 mean?
The ECU contains a processor that does all the engine calculations, and it monitors itself. This code means it has spotted an error in that processor or in its internal operation. Before replacing it, rule out the battery, earths and any available software updates.
Can you drive with P0606?
It may limit power or leave you stranded without warning. Drive carefully and get the car to a garage as soon as possible.
How do you clear P0606?
With an OBD2 scanner and an app like Final OBD, which clears it for free if it’s stored by the engine control unit. But clearing it only turns the light off: if the cause isn’t fixed, P0606 comes back.
Read it on your car
Final OBD reads the faults of every control unit for free, including each make’s own codes, and with Pro explains each one in plain English. Free clears engine faults at no cost.
Coming soon
Mid to late October 2026
If you want to try it in your car before anyone else, send us your email and we will add you as a tester.
info@finalobd.com