Can you keep driving?
Can you keep driving?
Stop driving if any of these apply
- !The check-engine light is flashing or the engine is shaking badly.
- !The vehicle is stalling, struggling to accelerate, or obviously running rough.
What to check first
Step-by-step checks
- 1
Safety first
If the check-engine light is flashing, avoid driving hard because the misfire can damage the catalytic converter
- 2
Free - no tools
Confirm whether P0311 appears with P0300 or other cylinder misfire codes
- 3
Basic tool needed
Inspect the spark plug, coil, and injector for cylinder 11 if the engine layout allows it
- 4
Basic tool needed
Look for a vacuum leak or intake leak near that cylinder
- 5
Basic tool needed
Check whether the misfire gets worse under load or at idle
If the code returns
- -If the plug, coil, or injector tests poorly, address that part before looking deeper.
- -If the misfire follows the coil or plug during a swap test, the part is the stronger suspect.
- -If fuel and ignition look normal, inspect compression and air leakage on that cylinder.
Background
What this code means
P0311 is a generic OBD-II code for a misfire on cylinder 11.
It usually points to a cylinder-specific combustion problem rather than a random misfire across the whole engine.
Diagnosis
Common causes
Worn spark plug
The plug may be fouled, worn, or not firing reliably.
Weak ignition coil
The coil may not be producing a strong spark under load.
Injector fault
The injector may be clogged, weak, or not delivering fuel evenly.
Compression or air leak problem
A mechanical fault can also make one cylinder misfire.
Avoid these mistakes
What not to do
- xDo not keep driving if the engine is flashing and the misfire is active.
- xDo not replace several ignition parts at once without confirming which cylinder is actually failing.
Parts
Parts that may need replacing
See also
Related OBD codes
Source notes
Generic OBD-II (SAE J1979 / ISO 15031-5). P0311 was seeded from dtcdb and then expanded as a conservative cylinder-specific misfire guide with focus on ignition, fuel, and compression checks.
This guide is written as a generic multi-make reference, so bulletin history, sensor locations, and repair order can still change by manufacturer and engine family.
This is generic OBD-II guidance and should not override vehicle-specific service information. Exact diagnosis and repair steps vary by make, engine family, and model year.
Last reviewed: 2026-04-10
Reference: Open reference