// Official meaning
ECM/PCM processor fault — the engine control module is reporting a problem with its own processor.
// On the bench
Like P0601, this is the ECU telling on itself. Thermal cycling cracks the solder around the processor, and on water-affected units — the Astra H pollen-filter leak that drips onto the ECU is notorious — corrosion finishes the job. New sensors and parts will not fix a processor fault; the board has to come to the bench.
How it shows up
- Check engine light, sometimes with limp mode
- Erratic idle, stalling or cutting out
- Multiple warning lights together
- Code returns after clearing
What fixing it involves
Component-level repair on the original unit — reflow and rework around the processor, water-damage cleanup where needed, then bench testing under load. From £150, typical around £190, coding and immobiliser data preserved.
Frequently asked questions
I keep replacing parts and the fault returns — why?
Because P0606 is an internal ECU fault, not a sensor fault. Parts money spent before the ECU is tested is usually wasted — which is exactly why we diagnose before anything is quoted.
Can a water-damaged ECU with P0606 be saved?
In most cases yes — ultrasonic cleaning, track repair and component replacement. We are upfront when damage is beyond economic repair, and can usually clone your data to a donor unit instead.