Fuel pump relay control low.
P0628 — also written PO628, P 0628, 0628 — is the OBD-II code for fuel pump relay control circuit low. Same code, same fix: this page covers every spelling of it.
Basically, the ECU is trying to turn the fuel pump on but isn't seeing the voltage it expects back from the relay. Total non-starter, and common as muck on Vauxhalls and Fords with a bit of age on them.
P0628 is a electrical fault code, typically costing £50–£300 to put right in a UK garage.
What P0628 actually feels like to drive
- Car cranks over perfectly but refuses to fire up (like it's out of petrol).
- Sudden cutting out while driving, especially after hitting a pothole or speed bump.
- A faint clicking sound coming from the fuse box that wasn't there before.
- The car starts fine when cold, but won't restart once you've popped into the shops and come back.
- Engine management light is on, sometimes accompanied by a 'Service Esc' or 'Fuel Mode' message on the dash.
What causes P0628?
- Relay failure
- Wiring open
UK vehicles that throw P0628 most often
- Vauxhall Astra J 1.7 CDTi (2009-2015) - Loom rub issues.
- Ford Focus Mk2 1.6/1.8 TDCi (2005-2011) - Corroded fuse box (PJB).
- Land Rover Freelander 2 (2006-2014) - Fuel pump relay failure.
- Volkswagen Golf Mk5 1.9 TDI (2004-2009) - Relay 109 or pump trigger issues.
- Vauxhall Insignia A 2.0 CDTi (A20DTH) - Fuel pump control module failures.
How P0628 is fixed
- Relay replacement
The P0628 misdiagnosis that wastes money
The amount of folks who jump straight to a £400 fuel pump replacement is frightening. They see 'fuel pump' in the code description and stick a new VDO or Bosch unit in the tank, only to find the car still won't fire. 90% of the time on something like an older Mondeo or a Corsa, it’s not the pump at all—it’s a corroded wire in the loom near the wheel arch or a £10 relay that's fused shut. Don't let a garage charge you for a pump until they've actually checked if there's 12v reaching the connector.
What a UK garage should charge for P0628
If it's just the relay, you're looking at £15 for a Bosch or Hella part and maybe £40 labour. If we’re hunting for a broken wire in the loom, expect a £60-£90 diagnostic fee. A main dealer will easily double that. If the actual sub-loom needs replacing, you're looking at £250-£300 all-in. Don't buy the cheapest unbranded relays off eBay; they’re rubbish and can actually melt your fuse board.
P0628 repair cost in the UK
Most P0628 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 P0628
If your car has 'cut out' and won't restart, tell the garage to do a 'voltage drop test' on the fuel pump relay circuit specifically. Don't just ask them to 'read the codes'—anybody with a £20 scanner can do that. Insist they check the relay base for 'green crusties' (corrosion). A good trick I use: swap the fuel pump relay with the horn relay if they're the same part number in the fuse box. If the horn stops working but the car starts, you've just saved yourself a two-hour diagnostic fee.
Can you drive with P0628?
May not start.
Urgency: high.