P0068
PowertrainMAP/MAF - Throttle Position Correlation
Usually a small job, not an engine-out nightmare. The ECU compares what the throttle position sensor says you're asking for against what the MAP or MAF sensor reckons is actually flowing into the engine, and when those two numbers don't agree it flags P0068. On turbo and supercharged petrols especially, this most often comes down to a split boost hose or a leaking intake pipe letting unmetered air in, so the air actually reaching the cylinders no longer matches the readings. Get it scanned and the cause is usually obvious once you've had a look round the intake.
ⓘ Information only. This page provides general educational information about fault code P0068. We do not assess the urgency or safety implications of any specific fault. That requires in-person diagnosis by a qualified mechanic. Full terms.
Recommended next steps
Whether a fault is urgent, drivable, or routine depends entirely on the cause on a specific vehicle, and that can only be determined by a qualified mechanic with diagnostic equipment. If a warning light is illuminated, the most reliable next step is professional diagnosis.
What does P0068 mean?
P0068 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: MAP/MAF - Throttle Position Correlation.
This is a standardised OBD-II code. The technical definition is the same regardless of the make or model of vehicle, although specific causes and symptoms can vary between vehicles.
Symptoms commonly associated with this code
Symptoms that drivers often report alongside this code. Not all may apply to every case:
- • Engine warning light on, sometimes with the car dropping into limp mode and refusing to boost properly
- • Hesitation or a flat spot when you put your foot down, particularly off-boost at low revs
- • Lumpy idle, sometimes a slight hunting up and down when sitting at the lights
- • Noticeable loss of power, the turbo feels like it's not pulling like it should
- • Occasional stall as you slow to a stop or come off the throttle
- • Fuel economy creeping up on the gauge, often the first thing owners moan about
Possible causes
Causes commonly associated with P0068, listed in approximate order of typical investigation. The actual cause on a specific vehicle can only be confirmed by professional diagnosis.
- 1. Split or popped-off intake/boost hose between the turbo and throttle body, the classic on boosted engines because that unmetered air throws the correlation right off
- 2. Vacuum leak at the intake manifold gasket, throttle body, or a perished hose, same effect of air sneaking in past the sensors
- 3. Dirty MAF sensor or a clogged air filter making the airflow reading read low against what the throttle is requesting
- 4. Faulty MAP sensor giving the ECU a duff pressure figure, common once the sensor port gets gummed up with oil mist on a turbo engine
- 5. Throttle position sensor worn or out of range, or carbon caked round the throttle body plate so it doesn't read its true position
- 6. Corroded or loose connectors at the MAP, MAF or throttle sensors, wiggle-test territory
- 7. Rare but real: an ECU calibration or software issue, only worth chasing once the mechanical stuff is ruled out
How mechanics typically diagnose
A typical diagnostic sequence used by mechanics, provided here for educational reference only. Diagnostic work should be performed by a qualified mechanic with the appropriate tools and training.
- 1. Plug in a scanner, log P0068 and any friends sitting alongside it like P0100 to P0105, then clear and road-test to confirm it's a live fault and not a one-off
- 2. With the engine running, go round every boost pipe, clamp and vacuum hose looking and listening for a leak. On a turbo a popped intercooler pipe is the usual culprit and you'll often hear it under load
- 3. Pull the air filter and check it isn't choked, and have a look at the MAF element for oil or muck, clean it with proper MAF cleaner if it's grubby
- 4. Check the wiring and plugs at the MAP, MAF and throttle sensors for green corrosion, chafing or a loose pin
- 5. Watch live data and compare throttle position against MAP and MAF as you gently blip the throttle. Healthy and they track together. If one lags or sits stuck while the other moves, you've found your bad sensor
- 6. If the intake's tight and the sensors track properly, look at the throttle body itself for carbon build-up holding the plate off its true closed position, clean and retest
Common questions about P0068
Can I carry on driving with a P0068 showing? +
You can usually limp it home and short journeys won't hurt, but I wouldn't leave it. On a turbo car this code often pushes the engine into limp mode, so you'll lose boost and power, which is dodgy if you need to overtake or pull onto a motorway. Beyond that, a persistent air leak or wrong sensor reading means the fuelling is off, and running rich or lean for weeks isn't kind to your cat or your spark plugs. Get it looked at within a few days rather than letting it ride for months.
Is this going to be an MOT failure? +
The stored code on its own isn't a fail. What the tester cares about is the engine warning light. If the MIL is lit when the car goes on the ramp, that's a straight fail now under the emissions and dashboard checks, regardless of the actual fault. Sort the underlying leak or sensor first, then let the light go out over a couple of drive cycles before you book it in, otherwise you've wasted a test fee.
What sort of money am I looking at to fix it? +
Depends entirely on what's caused it. A split boost hose or a new air filter and a MAF clean is cheap, often £20 to £60 in parts if you do it yourself, or an hour's labour at an independent. A replacement MAP, MAF or throttle position sensor fitted typically lands somewhere around £120 to £300 at a decent independent garage. A main dealer will usually charge more for the same sensor and labour, sometimes half again. If it turns out to be an intake manifold gasket or multiple sensors, you can be into the £400 plus bracket, but that's the exception rather than the rule with this code.
Information only, not professional advice
The information on this page is provided for general guidance and educational purposes only. It is not a substitute for diagnosis or repair advice from a qualified mechanic. Always verify any fault before paying for repairs. carfaultcodes.co.uk accepts no liability for decisions made based on this information. Full terms →