OBD
P030B
Ignition A Control Signal Circuit Low
What it means
P030B stands for Ignition A Control Signal Circuit Low. P030B is a P code, so the fault sits in the engine, transmission and emissions systems. For P030B, the second digit places it in ignition and misfire. For P030B, work through the cause list below, cheapest checks first.
What to check first
For P030B, pull the connector and inspect the terminals for spread, corrosion or backed-out pins before testing anything else.
Check these first
- P030B: Failing ignition coil, spark plug, or spark plug wire
- P030B: Faulty crankshaft or camshaft position sensor
- P030B: Wiring or connector damage in the ignition circuit
- P030B: Low compression or engine mechanical wear
- P030B: Incorrect ignition timing or a stretched timing chain
What to do next
P030B reports from the ignition and misfire system. These steps cover P030B in general, and the exact cause on your vehicle can differ from the cause named above.
- P030B: Read misfire counts and freeze frame data with an OBD-II scanner
- P030B: Test spark output and inspect spark plugs and coils
- P030B: Check crankshaft and camshaft position sensor signals while cranking
- P030B: Swap suspect ignition parts between cylinders to see if the fault moves
- P030B: Compression test if the issue persists on the same cylinder
Look up another code
Enter a full code or a symptom. Press / to search. How to read a code
Type a code above, or start from a symptom or a common code.
Updated
Generic SAE J2012 definition. Last updated 2026-08-30.