Fuel & air metering · Powertrain · generic (SAE-defined)
P0030: HO2S Heater Control Circuit (Bank 1 Sensor 1)
P0030 means the engine computer found a problem in the heater circuit of the upstream oxygen sensor on Bank 1, the sensor before the catalytic converter.
Standard title per SAE J2012 / ISO 15031-6 · Updated 2026-11-07 · By CarWhere Research
How P0030 sets
The heated oxygen sensor (HO2S) contains an electric heater that brings it to operating temperature quickly. The powertrain control module (PCM) controls the heater and monitors its circuit for correct voltage or current. If it detects an open, short or out-of-range condition in the Bank 1 Sensor 1 heater circuit, P0030 sets.
Common causes of P0030
Roughly most likely first; the actual cause depends on the vehicle and needs testing to confirm.
- Failed heater element inside the Bank 1 Sensor 1 oxygen sensor
- Damaged or melted sensor wiring near the exhaust
- Corroded or loose connector
- Blown oxygen sensor heater fuse
- Faulty heater relay where used
- PCM heater driver fault (rare)
P0030 symptoms
- Check engine light on
- Often no drivability symptoms
- Slightly worse fuel economy
- Longer time to enter closed-loop fuel control after a cold start
How P0030 is diagnosed
- Scan for codes and check for other heater or fuse-related codes
- Inspect the sensor wiring and connector for heat damage or chafing
- Check the heater fuse and power supply at the connector
- Measure heater resistance at the sensor and compare to specification
- Verify the PCM ground control signal for the heater
- Replace the faulty part and confirm the code does not return
Typical fixes for P0030
- Replace the Bank 1 Sensor 1 oxygen sensor
- Repair damaged wiring or connector
- Replace a blown fuse and correct the short
- Replace a faulty heater relay
Replace parts only after testing confirms the cause — a code names the circuit or condition that failed a check, not necessarily the faulty part. We don’t publish per-repair prices; for what households actually spend on upkeep, see car repair costs.
Related codes & warning lights
P0030 FAQ
What does code P0030 mean?
P0030 means the engine computer found a problem in the heater circuit of the upstream oxygen sensor on Bank 1, the sensor before the catalytic converter. The standard definition is "HO2S Heater Control Circuit (Bank 1 Sensor 1)."
Can I drive with a P0030 code?
Yes, the vehicle is generally safe to drive and usually runs normally. Fuel economy and emissions may suffer, especially on cold starts, and the vehicle may fail an emissions inspection until it is repaired.
Do I have to replace the whole oxygen sensor for P0030?
If the heater element inside the sensor has failed, yes, because the heater is not serviceable separately. Check the wiring and fuse first.
Which oxygen sensor is Bank 1 Sensor 1?
It is the upstream sensor, before the catalytic converter, on the side of the engine that has cylinder 1.
Keep researching
Engine guides by brand (known issues, specs)
More fuel & air metering codes
Sources
- SAE J2012 — Diagnostic Trouble Code Definitions (standard code titles)
- ISO 15031-6 — Road vehicles: communication between vehicle and external equipment for emissions-related diagnostics, Part 6: Diagnostic trouble code definitions
- U.S. EPA — Vehicle Emissions Inspection and Maintenance (I/M) programs
- U.S. EPA, 40 CFR 86.1806-17 — Federal onboard diagnostics requirements for light-duty vehicles
- California Air Resources Board — On-Board Diagnostic (OBD) Program
General information written by CarWhere Research, not a diagnosis of your vehicle. Manufacturers can add their own sub-definitions and test conditions; confirm with the factory service information for your year, make and model. Before paying for a repair, check NHTSA for open recalls and your warranty booklet: federal law requires an emissions warranty on major emission-control parts such as the catalytic converter and engine computer.