P0038
Fix within a few daysHeated Oxygen Sensor (HO2S) Heater Control Circuit High (Bank 1 Sensor 2)
Code P0038 means your downstream oxygen sensor's heater circuit has a high voltage. Common causes: Bad O2 sensor (85%), wiring issues (10%). Drivability: Yes, safe to drive. Repair cost: $75-$200 DIY, $150-$450 professional.
Can I Drive With P0038?
Yes, safe to drive
No restrictions, but expect reduced fuel economy and higher emissions.
Stop driving immediately if: Flashing CEL, loud noises, burning smell, rotten egg smell, significant power loss
Symptoms of P0038
- 1Check Engine Light is on
- 2Decreased fuel economy
- 3Engine may run slightly rough (less common)
- 4Failed emissions test
Common Causes of P0038
Parts most likely causing this code, ranked by probability
The heater element inside the oxygen sensor has failed, causing an open circuit or high resistance that the engine computer detects as high voltage.
85% of P0038 cases are fixed by replacing this part
Damaged, corroded, or shorted wiring or a faulty connector to the oxygen sensor's heater circuit can cause a high voltage reading.
10% of P0038 cases are fixed by repairing wiring or connectors
A rare internal fault within the engine computer's driver circuit for the oxygen sensor heater can cause this code.
5% of P0038 cases are fixed by replacing the ECM/PCM
Check These First (Before Buying Parts)
- Visually inspect the Bank 1 Sensor 2 oxygen sensor and its wiring for any obvious damage, fraying, or corrosion.
- Ensure the electrical connector to the sensor is fully seated and free of debris.
How to Diagnose P0038
- 1Visually inspect the Bank 1 Sensor 2 oxygen sensor and its wiring harness for any signs of damage, corrosion, or loose connections.
- 2Using a multimeter, check the resistance of the heater circuit on the oxygen sensor itself. Compare to factory specifications.
- 3With the ignition on, check for battery voltage and ground at the oxygen sensor connector to ensure power is reaching the heater circuit.
- 4If the sensor and wiring test good, use a scan tool to monitor live data for the oxygen sensor heater circuit. If all else checks out, consider a PCM issue (rare).
P0038 on Popular Vehicles
Honda Accord
2003-2012P0038 is very common on these models due to the downstream oxygen sensor heater failing. Replacement of the sensor is a direct fix.
90% fixed by replacing the oxygen sensor
Toyota Camry
2002-2011Similar to Honda, these Camry models frequently experience P0038 due to the Bank 1 Sensor 2 oxygen sensor heater circuit failing. It's a straightforward sensor replacement.
88% fixed by replacing the oxygen sensor
Ford F-150
2004-2014P0038 on F-150s often points to the downstream O2 sensor. While less common than on some imports, it's still the primary suspect. Check for exhaust leaks near the sensor as well, though less likely to cause a heater circuit code.
80% fixed by replacing the oxygen sensor
Frequently Asked Questions
What does P0038 mean?
P0038 indicates that the heater control circuit for your Bank 1 Sensor 2 oxygen sensor is reporting a high voltage. This sensor is located after the catalytic converter on the engine bank that contains cylinder #1.
Can I drive with P0038?
Yes, you can drive safely with a P0038 code. The engine will likely run in 'open loop' mode, meaning it won't use the downstream oxygen sensor for fuel trim adjustments. This will cause decreased fuel economy and higher emissions, but it will not cause immediate damage to your engine.
Will P0038 clear itself?
No, P0038 will not clear itself. The underlying issue, typically a faulty oxygen sensor heater, will remain. The Check Engine Light will stay on until the problem is fixed and the code is cleared, either by driving through several drive cycles after repair or by using a scan tool.
How do I fix P0038 myself?
Start by visually inspecting the oxygen sensor and its wiring for damage. If no damage is found, you will likely need to replace the Bank 1 Sensor 2 oxygen sensor. This usually involves disconnecting the electrical connector, unscrewing the old sensor with an O2 sensor socket, and installing the new one.
How much does it cost to fix P0038?
The cost to fix P0038 yourself is typically $75-$200 for the new oxygen sensor and an O2 sensor socket. If you take it to a professional shop, expect to pay $150-$450, which includes parts and labor.
P0038 keeps coming back - why?
If P0038 keeps returning, it usually points to an overlooked issue. Double-check the wiring harness for any intermittent shorts or open circuits, ensure the new sensor is the correct part for your vehicle, or in rare cases, investigate a potential issue with the engine's computer (PCM/ECM).
Will P0038 fail emissions/smog test?
Yes, P0038 will cause your vehicle to fail an emissions or smog test. The Check Engine Light being on is an automatic failure in most jurisdictions, and the faulty oxygen sensor heater means the emissions system is not operating correctly.
What's the difference between P0038 and P0037?
P0038 indicates a 'high' voltage in the oxygen sensor heater circuit, suggesting an open circuit or high resistance. P0037 indicates a 'low' voltage in the same circuit, which typically points to a short to ground or a low resistance issue. Both codes refer to the Bank 1 Sensor 2 heater circuit.
P0038 on Honda Accord?
P0038 is a common code on Honda Accords, particularly models from 2003-2012. The downstream oxygen sensor (Bank 1 Sensor 2) heater element is a known failure point. Replacing the sensor almost always resolves the issue for these vehicles.
Questions to Ask Your Mechanic
Did you test the resistance of the oxygen sensor's heater circuit?
Good answer: Yes, I measured the resistance and it was out of specification, indicating an internal failure of the heater element. We also confirmed voltage and ground at the connector.
Did you check the wiring harness for any shorts or open circuits to the sensor?
Good answer: Yes, I performed a continuity test on the wiring from the PCM to the sensor connector and found no breaks or shorts. The connector itself is also clean and secure.
Repair Cost Estimate
DIY Repair
Parts only
$75-$200
Shop Repair
Parts + labor
$150-$450
Save $75-$250 by doing it yourself
Difficulty
beginner
Time
0.5-1.5 hours
Beginner-friendly - The repair typically involves simple hand tools and an O2 sensor socket, making it accessible for most DIYers.
Cost of Waiting
Ignoring P0038 will lead to decreased fuel economy and higher emissions. While it won't immediately damage your engine, it will cause your vehicle to fail any required emissions tests. A $75-$150 sensor replacement now prevents ongoing fuel waste and emissions failures.
While You're In There...
Applying anti-seize to the threads of the new oxygen sensor prevents it from seizing in the exhaust pipe, making future removal easier.
If you need to remove any exhaust components to access the sensor, replacing old gaskets prevents exhaust leaks.
Tools You'll Need
- OBD-II scan tool
- Multimeter
- O2 sensor socket (7/8 inch or 22mm)
- Ratchet and extensions
- Penetrating oil
- Wire brush
P0038 is a very common sensor code. The repair is usually straightforward, and replacing the oxygen sensor will restore your vehicle's fuel economy and emissions performance.
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Your Next Steps
Step 1: Visually inspect the Bank 1 Sensor 2 oxygen sensor and its wiring harness for any physical damage, corrosion, or loose connections. Clean any visible corrosion.
Step 2: If the visual inspection doesn't reveal the problem, use a multimeter to test the resistance of the heater circuit on the oxygen sensor itself. Compare your reading to the manufacturer's specifications. Also, check for proper voltage and ground at the sensor's electrical connector.
Step 3: If the sensor's heater circuit resistance is out of spec or there's proper power to the connector but the code persists, replace the Bank 1 Sensor 2 oxygen sensor. Clear the code and perform a test drive.