P0038

HO2S Heater Control Circuit High Bank 1 Sensor 2

Oxygen sensor (heater) Generic OBD-II Medium

What it means

P0038 means the ECM detected high voltage (an open or high-resistance) in the heater control circuit of the bank 1, sensor 2 oxygen sensor — the downstream sensor after the catalytic converter. The heater brings the sensor up to operating temperature quickly; when its circuit faults, the car still drives normally but the check-engine light stays on and emissions monitors may not complete.

Medium

Can I keep driving? Yes — the car drives normally; this affects the downstream O2 sensor's heater, so the main effects are a warning light, slower emissions readiness, and a likely emissions-test failure.

Real-world scan data

Seen in

501

scans in the past year

Found in

0.1%

of scans

0.1%

of scans that found faults

Appears alongside · share of P0038 scans

P0137in 47.1% of scans

P0138in 46.5% of scans

P0133in 45.9% 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
Fails or won't complete an emissions/readiness test
Slightly reduced fuel economy in some cases
Often no noticeable change in how the car drives

Common causes

Most likely first

Open or high-resistance in the bank 1 sensor 2 O2 heater circuitLikely
Failed heater element inside the downstream oxygen sensorCommon
Corroded or loose connector at the sensorCommon
Damaged wiring or a blown heater fuseLess often
Faulty ECM (rare)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code names bank 1, sensor 2 (downstream).
Inspect the sensor connector and wiring for corrosion, melting near the exhaust, or a loose pin.
Check the O2 heater fuse and confirm power reaches the sensor.
Measure the sensor's heater resistance and compare to spec.
Replace the downstream oxygen sensor if the heater element is open or out of range.
Clear the code and drive a full cycle to confirm it stays off.

FAQ

Quick answers

Is it safe to drive with P0038?+

Yes, in the near term — the heater fault doesn't affect how the engine runs. It will keep the check-engine light on and can fail an emissions test, so plan the repair.

Can I just clear P0038?+

It returns once the ECM re-tests the heater unless the sensor or wiring is repaired.

Read & clear P0038 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