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.

Real-world scan data

Seen in

3,846

scans in the past year

Found in

0.6%

of scans

1.1%

of scans that found faults

Appears alongside · share of P0030 scans

P0036in 16.9% of scans

P0403in 7.2% of scans

P0110in 6.8% of scans

Figures reflect only diagnostic scans recorded through our own apps and tools. Cars are typically scanned because a symptom or warning light prompted it, so these counts describe our scan records — not the incidence of faults in any model, and not the quality, reliability, or safety of any vehicle. No comparison between manufacturers or models is implied. All trademarks belong to their respective owners; no affiliation or endorsement is implied.

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.

Read & clear P0030 yourself

Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.

▶ Get it on Google Play

✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX