DPF/cat exhaust temp sensor fault.
P2031 — also written P2O31, P 2031, 2031 — is the OBD-II code for exhaust gas temperature sensor (bank 1, sensor 2). Same code, same fix: this page covers every spelling of it.
This code means the temperature sensor sitting just after your catalytic converter or at the DPF inlet has given up the ghost. It's a classic plague on Euro 5 and Euro 6 diesel Vauxhalls and VWs.
P2031 is a sensors fault code, typically costing £100–£400 to put right in a UK garage.
What P2031 actually feels like to drive
- EML (Engine Management Light) stays on, usually accompanied by 'Service Required' message.
- Car goes into 'Limp Mode'—you'll have no poke when trying to overtake on the A9.
- DPF warning light comes on because the car has stopped its self-cleaning cycle.
- Noticeable drop in MPG as the ECU runs a rich safety map.
- The car might smell a bit 'sooty' or hot because it's trying to regen but failing.
What causes P2031?
- Sensor failure
- Wiring
UK vehicles that throw P2031 most often
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2009-2017
- Volkswagen Golf MK6/7 2.0 TDI (CFGB/CRBC) 2010-2018
- Ford Focus 1.6 TDCi (DV6) 2011-2015
- Land Rover Discovery Sport 2.0 TD4 (Ingenium) 2015-2019
- Mercedes-Benz C-Class C220d (OM651 engine) 2012-2016
- Audi A4 2.0 TDI (CGLC) 2012-2015
How P2031 is fixed
- Sensor replacement
The P2031 misdiagnosis that wastes money
I've seen so many lads just chuck a new DPF at this because the scanner says the filter is soot-clogged. What’s actually happening is the ECU sees a 'implausible signal' from P2031 and stops the car from doing a regeneration. You then get a 'DPF Full' message on the dash, but it’s the sensor that’s lied to the computer, not the filter that's dead. I’ve also seen folks change the wrong sensor—Sensor 2 is down by the DPF, not the one right behind the turbo. Check the live data before you spend a penny.
What a UK garage should charge for P2031
A decent diagnostic plug-in will cost you £50-£80 at an independent. A genuine or OE-quality sensor (like Delphi or Bosch) usually sits between £90 and £150 from factors like Euro Car Parts or GSF. Labour is usually an hour (£60-£90), but if it's rusted solid and needs the gas torches, expect that to double. You’re looking at £220-£300 all-in at a local shop, whereas a main dealer will easily rinse you for £450+ for the exact same job.
P2031 repair cost in the UK
Most P2031 repairs land between £100–£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 P2031
If you’re taking this to a garage, ask them to 'back-probe the sensor connector for 5V reference and ground.' If they look at you like you've got two heads, find another garage. These sensors are notorious for seizing into the exhaust pipe. I tell my customers: if it doesn’t come out with a bit of heat and a specialist split-socket, we might have to take the whole DPF off to get it on the bench, or even weld in a new boss. Insist on a Bosch or NGK part; the cheap £25 eBay sensors last about three weeks in a Scottish winter before the salt kills them.
Can you drive with P2031?
Drivable.
Urgency: medium.