P0043

HO2S Heater Control Circuit Low Bank 1 Sensor 3

Q: Is it safe to drive with P0043?

Yes. This is a sensor-heater fault, not a running problem — the engine drives normally. Just fix it before an emissions test, since the readiness monitor won't complete.

Q: Can I just clear P0043?

It will clear, but it returns once the ECM re-tests the heater circuit. The underlying wiring or sensor fault has to be repaired for it to stay off.

Oxygen sensor heater Generic OBD-II Medium

What it means

P0043 means the ECM detected low voltage in the heater circuit of the Bank 1, Sensor 3 oxygen sensor — a deep-downstream sensor. The internal heater brings the sensor to operating temperature quickly so it can read exhaust oxygen accurately. The car still drives fine, but the fault trips the check-engine light and blocks the emissions readiness monitor from completing.

Medium

Can I keep driving? Yes — the car drives normally, but the affected oxygen sensor warms up slowly, so expect a check-engine light and a likely emissions-test failure until it's fixed.

Real-world scan data

Seen in

scans in the past year

Found in

<0.1%

of scans

<0.1%

of scans that found faults

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
Failed or incomplete emissions test (readiness monitor won't set)
Slightly reduced fuel efficiency
Usually no change in how the car drives or feels

Common causes

Most likely first

Failed oxygen sensor heater element (Bank 1, Sensor 3)Likely
Short-to-ground or open in the heater control wiringCommon
Corroded or loose connector at the sensorCommon
Blown fuse feeding the heater circuitLess often
Faulty ECM/PCM driver (rare — check wiring and sensor first)Less often

How to diagnose & fix

Work through it in order

Read freeze-frame data and confirm the code is current, not a one-time glitch.
Inspect the Bank 1 Sensor 3 connector and wiring for corrosion, chafing, or a loose pin.
Check the heater fuse, then measure heater element resistance against spec.
Verify power and ground reach the heater connector with the key on.
If wiring, fuse, and power are good, replace the oxygen sensor. Clear and re-test.

FAQ

Quick answers

Is it safe to drive with P0043?+

Yes. This is a sensor-heater fault, not a running problem — the engine drives normally. Just fix it before an emissions test, since the readiness monitor won't complete.

Can I just clear P0043?+

It will clear, but it returns once the ECM re-tests the heater circuit. The underlying wiring or sensor fault has to be repaired for it to stay off.

Read & clear P0043 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