What P0068 means
The engine control module compares the air quantity measured by the manifold pressure and/or mass air flow sensor with the quantity the throttle position leads it to expect.
How the engine computer detects it
P0068 is set when they do not match, typically because more air arrives than the nearly closed throttle allows, i.e. an air leak behind the throttle, or because the throttle body is dirty or a sensor reads wrong. On engines with electronic throttle this check protects throttle control, so the engine often goes into reduced power. Each sensor can be electrically fine on its own; regulations require such plausibility checks for input sensors with a code of their own.
Written from public technical sources and not yet checked by a mechanic. How we write these pages
Symptoms
- Check engine light on
- Reduced power mode
- Rough or unstable idle
- Jerking
Common causes
- Air leak behind the throttle: intake manifold, vacuum or MAP hoses Most likely
- Throttle body dirty Most likely
- Mass air flow or manifold pressure sensor faulty Possible
- Engine control software (manufacturer updates exist) Possible
- Camshaft timing out of position Less likely
How to diagnose P0068
- Read every stored code with an OBD-II scanner. If misfire or fuel trim codes are there too, fix those first: they often cause this one.
- Inspect the parts involved: throttle body, mass air flow sensor, manifold absolute pressure sensor, throttle position sensor, intake manifold.
- Work through the causes above from most to least likely, cheapest checks first.
- Clear the code and drive a full drive cycle to confirm the repair held.
Reading the code
- P
- Powertrain
- 0
- Generic (SAE) code
- 0
- Fuel and air metering, auxiliary emission controls
- 68
- Specific fault
Questions drivers ask
Can I drive with code P0068?
Drive gently and only as far as you need to. The engine computer may limit power to protect the engine, so avoid highways and heavy traffic until it's fixed. If the check engine light starts flashing, pull over.
Will my car pass an emissions inspection with P0068?
Probably not in states that test vehicles with an OBD-II scan: an emissions-related code that keeps the check engine light on is usually an automatic fail. Rules differ by state and county, so check yours.
Will P0068 clear by itself?
The light can go off after several drive cycles without the fault, but the code returns if the cause is still there. After a repair, the readiness monitors need a full drive cycle before an inspection.
Can I fix P0068 myself?
Often yes, with an OBD-II scanner and basic tools. Difficulty: medium. Start with the cheapest checks before replacing expensive parts.
This page is general information, not a substitute for a professional diagnosis. Repair costs are rough estimates for parts and labor and vary by vehicle and region.