The MAP sensor is reading above the maximum expected voltage.
P0108 — also written PO1O8, P 0108, 0108 — is the OBD-II code for map sensor circuit high input. Same code, same fix: this page covers every spelling of it.
This one usually means the engine computer is seeing a high voltage signal from the Manifold Absolute Pressure sensor, making it think the engine is under full load when it isn't. I see this most often on high-mileage Vauxhalls and older Fords where the intake is caked in carbon.
P0108 is a sensors fault code, typically costing £45–£280 to put right in a UK garage.
What P0108 actually feels like to drive
- The car feels 'flat' and gutless, almost like the turbo has packed in.
- Massive cloud of black smoke out the back when you try to overtake.
- A really lumpy, hunting idle that almost stalls at the traffic lights.
- The car 'kangaroos' or jerks violently when you lift off the throttle.
- Fuel economy has absolutely tanked—getting about 20mpg on a diesel.
What causes P0108?
- Failed MAP sensor
- Open circuit on ground or signal
- Blocked port sending false high
UK vehicles that throw P0108 most often
- Vauxhall Astra J 1.7 CDTi (A17DTR) 2009-2014
- Ford Focus Mk2 1.6 TDCi (DV6) 2005-2011
- Vauxhall Insignia 2.0 CDTi (A20DTH) 2008-2015
- Fiat 500 1.2 Fire Engine 2007-2020
- Honda Civic 2.2 i-DTEC 2012-2015
- Volkswagen Golf Mk6 1.6 TDI (CAYC) 2008-2013
How P0108 is fixed
- Replace MAP sensor
- Repair wiring
- Clean MAP port
The P0108 misdiagnosis that wastes money
I’ve lost count of how many times I’ve seen brand new sensors thrown at a car for P0108 only for the light to stay on. Lads often forget that 'Circuit High' can just mean the sensor isn't seeing any vacuum at all. On those older Vauxhall Zafiras or Astras, the tiny vacuum pipe to the sensor gets brittle and snaps, or the port on the inlet manifold gets completely choked with EGR soot. The sensor thinks you're at full throttle even when you're idling, so it sends a high voltage signal. It’s usually a blocked hole or a £5 bit of rubber pipe, not the sensor itself.
What a UK garage should charge for P0108
An initial diagnostic plug-in will set you back £50 to £80 at a decent indie. If it’s just a split vacuum hose, you’re looking at maybe £30 in labour and a few quid for the pipe. If the sensor is actually knackered, a quality Bosch or Denso part from the factors is usually £60 to £110. Avoid the £15 eBay specials; they’re rubbish. Total job at a local garage usually lands between £120 and £180. If you go to a main dealer, expect that to double once they add their 'premium' hourly rate and mark up the genuine boxed part.
P0108 repair cost in the UK
Most P0108 repairs land between £45–£280 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 P0108
Before you let a garage charge you for a new sensor, ask them: "Have you checked the live data for the barometric pressure versus the MAP reading with the engine off?" They should match. If the MAP is stuck high while the engine is off, it’s likely the sensor or wiring. If it only acts up when running, it’s a vacuum or blockage issue. Also, insist they check the plug for 'green death'—that’s corrosion in the terminal. If they just swap the part and don't clean the connector, you'll be back in a week with the same light on.
Can you drive with P0108?
Drivable, limp mode likely.
Urgency: medium.