OBD Cylinder 8 Air-Fuel Ratio Imbalance - Adjustment At Limit During Balance
What it means
P231B stands for Cylinder 8 Air-Fuel Ratio Imbalance - Adjustment At Limit During Balance. P231B is a P code, so the fault sits in the engine, transmission and emissions systems. For P231B, the second digit places it in ignition and misfire. For P231B, work through the cause list below, cheapest checks first.
What to check first
For P231B, read the stored codes from every module, not just the engine, because related codes often name the same fault more precisely.
Check these first
- P231B: Failing ignition coil, spark plug, or spark plug wire
- P231B: Faulty crankshaft or camshaft position sensor
- P231B: Wiring or connector damage in the ignition circuit
- P231B: Low compression or engine mechanical wear
- P231B: Incorrect ignition timing or a stretched timing chain
What to do next
P231B belongs to the ignition and misfire system. These are the general steps for P231B, and the exact cause on your vehicle can differ.
- P231B: Read misfire counts and freeze frame data with an OBD-II scanner
- P231B: Test spark output and inspect spark plugs and coils
- P231B: Check crankshaft and camshaft position sensor signals while cranking
- P231B: Swap suspect ignition parts between cylinders to see if the fault moves
- P231B: Compression test if the issue persists on the same cylinder
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Updated
Generic SAE J2012 definition. Last updated 2026-08-30.