Cam sensor voltage too high — open circuit likely.
P0343 — also written PO343, P 0343, 0343 — is the OBD-II code for camshaft position sensor a high input (bank 1). Same code, same fix: this page covers every spelling of it.
Basically, the ECU is seeing a constant high voltage from the cam sensor instead of a pulse, usually because the circuit is broken or the sensor's internals have fried. It's a classic headache on high-mileage German diesels and Ford Ecoboosts.
P0343 is a sensors fault code, typically costing £90–£400 to put right in a UK garage.
What P0343 actually feels like to drive
- The car takes ages to fire up (long cranking) before finally catching.
- Sudden 'jerk' or momentary cut-out while cruising at motorway speeds.
- Engine drops into 'Limp Mode' with a noticeable loss of puff.
- The Start-Stop system stops working and shows a dash error.
- The car runs perfectly once started, but the Engine Management Light stays glowing.
What causes P0343?
- Broken wire
- Failed sensor
UK vehicles that throw P0343 most often
- Volkswagen Golf/Passat 2.0 TDI (EA188/EA189) 2005-2015
- BMW 3 Series (N47/N57 engines) 2007-2014
- Ford Focus 1.0 Ecoboost (M1DA) 2012-2018
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2008-2015
- Mini Cooper/One 1.6 (N12/N16 engines) 2006-2013
How P0343 is fixed
- Replace sensor
- Repair loom
The P0343 misdiagnosis that wastes money
I see lads constantly throwing a cheap £20 sensor from eBay or a local factor at this, only for the car to come back the next day with the same EML on. On these VAG 2.0 TDIs or the BMW N47 engines, P0343 is often a 'liar code.' It flags high voltage because the signal wire has rubbed through against a bracket or the battery tray, causing an open circuit. I’ve even seen a jumped timing chain cause the signal to look 'stuck' high to the ECU, leading folk to change a perfectly good Bosch sensor when the engine is actually a ticking time bomb.
What a UK garage should charge for P0343
For a basic sensor swap on something like a Golf, you're looking at £40-£60 for a quality Bosch or Delphi sensor, plus an hour's labour at £60-£90. If it’s a BMW N47 where the sensor is tucked away at the back, labour climbs. A main dealer will easily sting you for £400 once you factor in their 'diagnostic fee' and 100% markup on parts. If the loom needs a professional solder repair because of a break, expect to pay around £150-£200 for the detective work and the fix.
P0343 repair cost in the UK
Most P0343 repairs land between £90–£400 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 P0343
Before you let a garage charge you for a new sensor, insist they do a 'continuity and load test' on the wiring harness. If the ECU sees 5V when it expects a pulsing signal, it’s usually a break in the loom, not the sensor itself. Also, if you’re driving a BMW or a Mini, ask them to check the oil for 'glitter'—I’ve seen P0343 pop up because the VANOS solenoids are clogged with metal shavings from a failing timing chain guide, messing with the camshaft's position. Don't just swap the part; check the health of the oil first.
Can you drive with P0343?
Yes.
Urgency: medium.