Fuel pump relay control high.
P0629 — also written PO629, P 0629, 0629 — is the OBD-II code for fuel pump relay control circuit high. Same code, same fix: this page covers every spelling of it.
This code means your ECU has detected too much voltage on the fuel pump relay circuit, usually because the relay's knackered or a wire's shorted to power. It’s a common 'no-start' culprit on older Vauxhall and Ford fleets.
P0629 is a electrical fault code, typically costing £50–£300 to put right in a UK garage.
What P0629 actually feels like to drive
- Car cranks over perfectly but won't catch or fire at all.
- A sudden 'engine malfunction' message follows a sharp jolt or hitting a pothole.
- You can't hear the usual 'prime' hum from the rear seat when you turn the ignition.
- Intermittent stalling specifically when the engine bay gets up to temperature.
- The fuel pump fuse keeps blowing the second you turn the key to position two.
What causes P0629?
- Relay short
- Wiring
UK vehicles that throw P0629 most often
- Vauxhall Astra J / Insignia A (A20DTH engines) 2009-2015
- Ford Focus Mk2 / Mk3 1.6 & 2.0 TDCi 2007-2016
- Volkswagen Golf Mk6 2.0 TDi 2008-2013
- Nissan Qashqai J10 1.5 dCi 2007-2013
- Land Rover Discovery 3 / 4 TDV6 2004-2016
- Ford Transit Custom 2.2 TDCi 2012-2018
How P0629 is fixed
- Relay replacement
The P0629 misdiagnosis that wastes money
I’ve seen too many lads just chuck a new fuel pump at this because the car won't start and they hear the word 'Fuel' on their scanner. It’s a total waste of the gaffer's time and the customer's brass. P0629 is about the control circuit—the wiring or the relay—not the pump itself. Usually, it's a £5 relay that's internally shorted or a bit of wiring that's rubbed through on a bracket, sending a 12v signal right back to the ECU where it isn't wanted. Check your fuses and swapsies the relay first before you go dropping a fuel tank.
What a UK garage should charge for P0629
For a basic relay swap using a quality Bosch or Hella part, you're looking at £50 to £80 including 30 mins of my time. If I have to start chasing a short in the loom under the battery tray, the bill will climb to £150-£250 depending on how deep the rot goes. A main dealer will likely sting you for a £120 'diagnostic fee' before they even open the bonnet, plus they'll charge double for the same OE relay I get from the local factor.
P0629 repair cost in the UK
Most P0629 repairs land between £50–£300 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 P0629
Don't let a garage quote you for a 'full fuel system overhaul' right off the bat. If you've got P0629, ask them specifically if they've checked the relay resistance and performed a 'wiggle test' on the wiring loom near the fuse box. A proper diagnostic should involve a multimeter, not just a parts catalogue. If you're stuck on the side of the A9, sometimes swapping the fuel pump relay with the air-con relay (if they're the same part number in the fuse box lid) can get you home. Just check the diagram first so you don't blow the ECU.
Can you drive with P0629?
Drivable.
Urgency: high.