ECU processor error.
P0606 — also written PO6O6, P 0606, 0606 — is the OBD-II code for control module processor fault. Same code, same fix: this page covers every spelling of it.
This code means the car's brain—the Engine Control Module—has tripped over its own feet. It's common on Vauxhalls where the ECU sits right on the vibrating engine, or VAG cars where the rain drains get blocked.
P0606 is a electrical fault code, typically costing £80–£1500 to put right in a UK garage.
What P0606 actually feels like to drive
- The car goes into 'Limp Mode' without warning on the A9, losing all power.
- The dash lights up like a Christmas tree—ABS, Traction Control, and Engine lights all on at once.
- Total 'No Start' condition—you turn the key and absolutely nothing happens.
- The engine cooling fans run at full speed as soon as you turn the ignition on.
- Intermittent stalling at roundabouts that leaves you stranded for 5 minutes before it magically restarts.
What causes P0606?
- Failed ECU
- Water damage
- Bad ground
UK vehicles that throw P0606 most often
- Vauxhall Astra J 1.4 Turbo (2009-2015) - A14NET engine
- Vauxhall Corsa D 1.2/1.4 (2006-2014) - Engine-mounted ECU vibration failure
- VW Golf Mk5/Mk6 1.9/2.0 TDI - Water ingress in the plenum chamber
- Ford Focus 1.6 TDCi (2005-2011) - Corroded PCM pins due to moisture
- Vauxhall Insignia 2.0 CDTi (A20DTH) - Internal processor software errors
- Peugeot 207 1.4/1.6 VTi - ECU internal hardware failure
How P0606 is fixed
- Test grounds
- Replace or repair ECU
The P0606 misdiagnosis that wastes money
I see lads throwing new coils, plugs, and even throttle bodies at this because the car is stuttering or won't start, thinking it's a sensor issue. They’re wasting their brass. P0606 isn't a sensor failing; it’s the 'brain' itself having a stroke. Nine times out of ten, they’ve missed that a clogged plenum chamber has turned the ECU into a submarine. By the time they bring it to me, they’ve spent £300 on parts the car didn't need, when the ECU terminals were already green with corrosion.
What a UK garage should charge for P0606
A basic diagnostic to confirm it’s not just a bad earth will run you £70-£90. If it’s a software glitch, a main dealer re-flash is usually £150-£200. Sending your unit away for a professional rebuild/repair/clone typically costs between £250 and £450 including carriage. If you’re forced to buy a brand new Bosch or Delphi unit from the dealer, you’re looking at £1,200 for the part alone, plus another £200 for 'virginising' and programming it to the VIN.
P0606 repair cost in the UK
Most P0606 repairs land between £80–£1500 including parts and labour. The spread is wide because the cheap fix (a sensor, a hose, a leak) and the expensive fix (a major component) throw the same code — which is why a proper diagnosis before parts are bought saves the most money.
Bob's tip on P0606
Don't let a garage talk you into a £1,500 new unit straight off the bat. The first thing I do is check for software TSBs (Technical Service Bulletins)—sometimes a simple flash update at a specialist fixes a 'check sum' error. If it is hardware, don't buy a second-hand ECU off eBay; it'll be 'locked' to the donor car's immobiliser. Instead, ask for a 'clone' service. You send your dead unit and a matching used one to a specialist like ECU Testing in Derbyshire—they swap the data over so it’s plug-and-play when it comes back. Saves you a fortune in coding fees.
Can you drive with P0606?
May run erratically.
Urgency: high.