Heated Oxygen Sensor Heater Control Circuit Low (Bank 1, Sensor 3)
The P0043 code means the vehicle's onboard diagnostic system has detected: Heated Oxygen Sensor Heater Control Circuit Low (Bank 1, Sensor 3). This is a low severity code.
- Keep driving?
- Yes, but fix soon
- DIY difficulty
- moderate
- Estimated cost
- $100 - $300 (parts and labor)
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Common Symptoms
- Check Engine Light on
- Marginally reduced fuel economy
- Longer O2 sensor warm-up period
- Emissions test failure possible
Probable Causes (Ranked by Likelihood)
- Failed O2 sensor heater element Very High
- Open circuit in heater wiring High
- Corroded connector at O2 sensor Moderate
- Blown heater circuit fuse Moderate
Step-by-Step Diagnostic Procedure
-
Confirm P0043 and identify Bank 1 Sensor 3 location
-
Check heater circuit fuse and relay
-
Measure voltage at O2 sensor heater connector
-
Test heater element resistance in the O2 sensor
Frequently Asked Questions
What does P0043 mean?
P0043 indicates a low voltage condition in the heater circuit of the Bank 1 Sensor 3 oxygen sensor, typically caused by an open circuit or failed heater element.
Is P0043 serious?
P0043 is a low severity code. It primarily affects emissions during cold starts and may cause a slight drop in fuel economy.
How do I fix P0043?
The most common fix is replacing the Bank 1 Sensor 3 oxygen sensor. In some cases, repairing wiring or replacing a fuse resolves the issue.
Sources
This page is built from documented references. Verify against your own service info before repair work.
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