HO2S Heater Control Circuit High (Bank 1 Sensor 2)
What does P0038 mean?
The P0038 code means the vehicle's onboard diagnostic system has detected: HO2S Heater Control Circuit High (Bank 1 Sensor 2). This is a low severity code.
Common Symptoms
- Check Engine Light on
- O2 heater fuse may blow repeatedly
- Slightly reduced fuel economy
- No major drivability issues
- Failed emissions test
Probable Causes (Ranked by Likelihood)
- Shorted heater element inside the downstream O2 sensor Very High
- Short to power in the heater circuit wiring High
- Water intrusion or corrosion in the sensor connector Moderate
- Damaged wiring insulation causing a short Moderate
- PCM heater driver failure Low
Step-by-Step Diagnostic Procedure
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Check the O2 heater fuse. A high circuit fault often blows the fuse. Note if it blows again after replacement.
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Disconnect the bank 1 sensor 2 O2 sensor and measure heater resistance (2-15 ohms typical). Very low resistance (under 1 ohm) indicates a shorted heater.
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With the sensor disconnected, check if the code clears after a drive cycle. If so, the sensor is the problem. If the code persists, suspect wiring.
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Inspect the harness for chafed or melted insulation causing a short to ground or power. Pay attention to routing near the exhaust and underbody.
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Check the sensor connector for moisture intrusion or corroded pins that could cause an unintended short.
Frequently Asked Questions
Can I drive with code P0038?
Yes, you can drive normally. However, if the shorted sensor is blowing fuses repeatedly, other components on the same fuse circuit could be affected. Fix it promptly to avoid electrical issues.
What does high circuit mean for P0038?
High circuit means the PCM detected excessive current flowing through the O2 sensor heater circuit. This is usually caused by a shorted heater element inside the sensor or a short to power in the wiring, allowing more current than designed.
Can I just pull the fuse to stop it from blowing?
Removing the fuse will stop the immediate problem but may disable other sensors or systems on the same circuit. It is better to disconnect the faulty sensor or replace it to properly fix the issue.