OBD NOx Sensor Heater Control Circuit High Bank 1 Sensor 3
What it means
P23B3 stands for NOx Sensor Heater Control Circuit High Bank 1 Sensor 3. P23B3 is a P code, so the fault sits in the engine, transmission and emissions systems. For P23B3, the second digit places it in ignition and misfire. For P23B3, work through the cause list below, cheapest checks first.
Where it lives
For P23B3, the circuit described runs through the sensor. The description of P23B3 puts it on bank 1.
What to check first
For P23B3, check the bank 1 reading against the other bank before buying parts, since if only one side is out of range that side is the fault.
Check these first
- P23B3: Failing ignition coil, spark plug, or spark plug wire
- P23B3: Faulty crankshaft or camshaft position sensor
- P23B3: Wiring or connector damage in the ignition circuit
- P23B3: Low compression or engine mechanical wear
- P23B3: Incorrect ignition timing or a stretched timing chain
What to do next
P23B3 belongs to the ignition and misfire system. These are the general steps for P23B3, and the exact cause on your vehicle can differ.
- P23B3: Read misfire counts and freeze frame data with an OBD-II scanner
- P23B3: Test spark output and inspect spark plugs and coils
- P23B3: Check crankshaft and camshaft position sensor signals while cranking
- P23B3: Swap suspect ignition parts between cylinders to see if the fault moves
- P23B3: 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.