The IAT reading is present but doesn't move as expected with engine warm-up.
P0111 — also written PO111, P 0111, 0111 — is the OBD-II code for iat sensor range/performance. Same code, same fix: this page covers every spelling of it.
This code means your engine's thermometer has 'frozen' at one temperature, usually because the sensor tip is caked in oil or the internal resistor has snapped. It's incredibly common on high-mileage German diesels like the BMW N47 or VW 2.0 TDI.
P0111 is a sensors fault code, typically costing £30–£300 to put right in a UK garage.
What P0111 actually feels like to drive
- The car feels 'gutless' pulling away from roundabouts when it's warm.
- Fuel economy has dropped by 5-8 mpg for no apparent reason.
- Engine 'pinks' or rattles slightly under heavy load in summer.
- The EML light is on, but the car drives mostly fine otherwise.
- Slight hesitation or a 'flat spot' at 2,000 RPM.
What causes P0111?
- Failed IAT element (often built into MAF)
- Sensor contaminated with oil vapour
UK vehicles that throw P0111 most often
- Vauxhall Astra J 1.7 CDTi (A17DTE) 2009-2015
- BMW 320d (N47) 2007-2013
- Ford Focus 1.6 TDCi (DV6) 2011-2018
- Volkswagen Golf MK6 2.0 TDI 2008-2013
- Land Rover Freelander 2 2.2 SD4 2010-2014
- Audi A4 2.0 TDI (CAGA engine) 2008-2015
How P0111 is fixed
- Replace IAT/MAF assembly
- Clean IAT tip
The P0111 misdiagnosis that wastes money
I see people throwing cheap £20 eBay MAF sensors at this all the time, but on the Vauxhall 1.7 CDTi engines, the IAT is often a separate little sensor tucked away in the boost pipe. Lads will swap the expensive airflow meter, clear the code, and it’s back five miles later. I’ve also seen plenty of folk ignore the wiring harness near the radiator fan—vibration rubs the loom raw, and you get a 'ghost' reading that stays static regardless of how hard you’re driving.
What a UK garage should charge for P0111
A basic diagnostic plug-in will cost you £40–£60 at an indie. If it’s just a dirty sensor, a £10 tin of CRC Mass Air Flow cleaner might fix it. If the sensor is part of the MAF unit, a genuine Bosch or Denso replacement from a factor like Euro Car Parts will run you £90–£160 plus 30 mins labour. If you go to a main dealer, expect to pay £300+ once they've added their 'premium' labour rate and VAT.
P0111 repair cost in the UK
Most P0111 repairs land between £30–£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 P0111
Before you let a garage sell you a £200 Bosch MAF, ask them to do a 'cold soak' check. Hook up the diagnostic tool first thing in the morning before starting the car. The IAT and Coolant (ECT) readings should be within 2 degrees of each other. If the coolant says 10°C and the intake says 45°C, the sensor is toast. Also, insist they check for oil blow-by; if your turbo is tired, it sprays oil mist onto the sensor tip, insulating it so it can't read temperature changes properly.
Can you drive with P0111?
Yes.
Urgency: low.