OBD NOx Sensor Heater Resistance Bank 1 Sensor 1
What it means
P224A stands for NOx Sensor Heater Resistance Bank 1 Sensor 1. P224A is a P code, so the fault sits in the engine, transmission and emissions systems. For P224A, the second digit places it in injector circuits. For P224A, work through the cause list below, cheapest checks first.
Where it lives
For P224A, the description names the sensor as the part involved. The description of P224A puts it on bank 1.
What to check first
For P224A, compare the reading on bank 1 against the other bank on the same scan tool, because a bank that reads differently from its twin is the fault.
Check these first
- P224A: Faulty or contaminated sensor in the fuel/air metering circuit
- P224A: Damaged or shorted wiring or connector for the affected circuit
- P224A: Vacuum leak or intake system restriction
- P224A: Failing fuel pump, injector, or fuel pressure regulator
What to do next
P224A reports from the injector circuits system. These steps cover P224A in general, and the exact cause on your vehicle can differ from the cause named above.
- P224A: Read freeze frame data and related codes with an OBD-II scanner
- P224A: Inspect the affected sensor wiring and connector for damage
- P224A: Compare live sensor readings (fuel trim, airflow, temperatures) to manufacturer specs
- P224A: Smoke test the intake system if lean or vacuum conditions are suspected
- P224A: Replace the failed component after confirming it with live data
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.