Bank 2 running lean.
P0151 — also written PO151, P 0151, 0151 — is the OBD-II code for o2 sensor low voltage (bank 2 sensor 1). Same code, same fix: this page covers every spelling of it.
This one means the front oxygen sensor on the 'secondary' side of the engine is seeing way too much oxygen, usually because of a cheeky air leak or a tired sensor. Most common on V6 petrol Jags and BMWs where the rear bank gets roasted by engine heat.
P0151 is a sensors fault code, typically costing £80–£500 to put right in a UK garage.
What P0151 actually feels like to drive
- The car feels 'flat' or hesitant when you pull away from a roundabout.
- Idle feels lumpy, like it's hunting for the right RPM at traffic lights.
- Noticeable drop in MPG - you're getting fewer miles to the tankful.
- The engine might 'pink' or rattle slightly under heavy load (climbing hills).
- The EML (Check Engine Light) is staring you in the face on the dash.
What causes P0151?
- Vacuum leak
- Sensor
- Fuel pressure
UK vehicles that throw P0151 most often
- BMW 3 Series 325i/330i (N52/N53 engines) 2005-2013
- Jaguar XF 3.0 V6 Petrol 2008-2015
- Range Rover Sport 4.4 / 5.0 V8 Petrol 2005-2013
- Audi A6 2.4 / 3.2 FSI V6 2004-2011
- Vauxhall Omega 2.5 / 3.0 V6 (The old 'shonky' ones)
- Mercedes C320 / E320 V6 (M112 engine) 2000-2006
How P0151 is fixed
- Smoke test
- Sensor replacement
The P0151 misdiagnosis that wastes money
I can't tell you how many folk come in after DIY-ing a new Bosch O2 sensor from Euro Car Parts, only to find the light pops back on two days later. They assume the new part is a dud, but 9 times out of 10, they've ignored a tiny split in a vacuum breather pipe or a perished intake boot. On things like the Range Rover Sport V8, a 'lean' code usually means the engine is sucking in unmetered air after the MAF sensor, making the computer think the sensor has died because it's pegged at low voltage. It’s rarely the sensor; it’s usually the air getting in where it shouldn't.
What a UK garage should charge for P0151
A proper diagnostic plug-in and live data check will run you £50 to £80 at a good indie. If it’s just a vacuum leak, a bit of hose and labour might be £100. If the sensor is genuinely shot, a quality NTK or Bosch sensor is usually £90-£150 plus an hour's labour (£60-£90). If you go to a main dealer, expect a £180 diagnostic fee and a £250+ VAT bill for the part alone. Total job usually sits between £150 and £400 depending on how rusted that sensor is into the manifold.
P0151 repair cost in the UK
Most P0151 repairs land between £80–£500 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 P0151
If your garage says 'it's the sensor' without even lifting the bonnet, walk away. Insist on a 'smoke test'. We hook a machine up that pumps thick white smoke into the intake system; if there's a vacuum leak, the smoke pours out of the hole like a chimney. It costs about £40-£60 for the test but saves you hundreds in parts-cannon guesswork. Also, if you do need a sensor, don't buy the £25 unbranded rubbish off eBay; they have the wrong resistance and will fail your next MOT on emissions. Stick to Denso or NGK/NTK.
Can you drive with P0151?
Drivable.
Urgency: medium.