P0030
HO2S Heater Control Circuit Bank 1 Sensor 1
Emissions / O2 sensor
Generic OBD-II
Medium
What it means
P0030 means the ECM has found a fault in the heater circuit of the upstream oxygen sensor on bank 1 (sensor 1). The heater brings the sensor to operating temperature quickly so the engine can enter closed-loop fuel control. With the heater faulty, the sensor warms slowly — the engine still runs fine, but emissions and warm-up economy can suffer.
Medium
Can I keep driving? Safe to drive — the engine runs normally. The oxygen sensor just heats up slower, delaying closed-loop fuel control, so expect a warning light and possibly a failed emissions test until fixed.
Common symptoms
What you'll notice
- Check-engine light on
- Slightly reduced fuel economy, especially during warm-up
- Failed or incomplete emissions readiness / smog test
- Longer time to enter closed-loop fuel control
Common causes
Most likely first
- Failed oxygen-sensor heater element (upstream, bank 1 sensor 1)Likely
- Blown fuse or damaged wiring in the heater circuitCommon
- Corroded or loose sensor connector, or poor groundCommon
- Failed PCM heater driver (rare)Less often
How to diagnose & fix
Work through it in order
- Scan and confirm the code, then locate the upstream sensor on bank 1.
- Check the heater-circuit fuse and inspect the connector for corrosion or looseness.
- Measure the sensor's heater resistance and compare against specification.
- Verify power and ground reach the heater circuit; repair any wiring faults.
- Replace the oxygen sensor if the heater element has failed; check the PCM driver last.
FAQ
Quick answers
Is it safe to drive with P0030?+
Yes. The heater fault mainly delays closed-loop operation and may affect emissions and warm-up economy. It won't leave you stranded, but fix it to pass an emissions test.
Can I just clear P0030?+
It will come back once the sensor heater is retested unless the heater element or its circuit is repaired. Clearing alone doesn't fix it.
Related codes
Often seen with P0030
Read & clear P0030 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX