P0135
Fix within 1-2 weeksYour upstream oxygen sensor (Bank 1 Sensor 1) isn't heating up properly. This sensor needs to be hot to accurately measure exhaust gases and help your engine run efficiently.
Code P0135 means your upstream oxygen sensor's heater circuit isn't working. Common causes: Failed O2 sensor (85%), wiring issues (10%). Drivability: Yes, safe to drive, but fix within 1-2 weeks. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0135?
Yes, safe to drive
No restrictions, but fix within 1-2 weeks to avoid long-term issues.
Stop driving immediately if: Flashing CEL, loud noises, burning smell, rotten egg smell, significant power loss
Symptoms of P0135
- 1Check Engine Light is on
- 2Reduced fuel economy (you're filling up more often)
- 3Engine may run rough or hesitate, especially when cold
- 4Increased exhaust emissions (you might smell it)
Common Causes of P0135
Parts most likely causing this code, ranked by probability
The heater element inside the oxygen sensor has failed, preventing it from reaching its operating temperature quickly.
85% of P0135 cases are fixed by replacing this part
Damaged wires, corroded pins, or a loose connection to the O2 sensor's heater circuit can prevent power from reaching the sensor.
10% of P0135 cases are fixed by repairing wiring or connectors
A blown fuse in the O2 sensor heater circuit will cut off power to the sensor, causing the heater to fail.
4% of P0135 cases are fixed by replacing a fuse
A rare internal fault in the PCM could prevent it from properly controlling or powering the O2 sensor heater circuit.
1% of P0135 cases are fixed by replacing the PCM
Check These First (Before Buying Parts)
- Visually inspect the O2 sensor wiring for any cuts, frays, or corrosion.
- Check the fuse for the O2 sensor heater circuit in your vehicle's fuse box.
How to Diagnose P0135
- 1Visually inspect the Bank 1 Sensor 1 oxygen sensor and its wiring for any signs of damage, fraying, or corrosion.
- 2Locate and check the fuse for the O2 sensor heater circuit in your vehicle's fuse box (consult your owner's manual).
- 3Using a multimeter, test the resistance of the heater circuit within the O2 sensor itself (unplugged).
- 4With the ignition on, test for power and ground at the O2 sensor connector to ensure the vehicle's wiring is supplying voltage.
- 5If all other checks pass, replace the Bank 1 Sensor 1 oxygen sensor.
P0135 on Popular Vehicles
Toyota Camry
2007-2024P0135 is a common code on higher mileage Toyota Camrys, often indicating a failed upstream O2 sensor heater element.
85% fixed by replacing the O2 sensor
Honda Accord
2003-2024Honda Accords frequently experience P0135 due to the upstream O2 sensor heater failing. This is a straightforward replacement.
85% fixed by replacing the O2 sensor
Ford F-150
2004-2024On Ford F-150s, P0135 is usually a failed O2 sensor, but wiring damage from road debris or corrosion is also a factor due to sensor placement.
80% fixed by replacing the O2 sensor, 15% by wiring repair
Frequently Asked Questions
What does P0135 mean?
P0135 indicates a malfunction in the heater circuit of your Bank 1 Sensor 1 oxygen sensor. This sensor is crucial for accurate fuel mixture control, especially when the engine is cold.
Can I drive with P0135?
Yes, you can drive safely with P0135. However, your fuel economy will suffer, and your vehicle will produce more emissions. Fix this within 1-2 weeks to prevent further issues.
Will P0135 clear itself?
No, P0135 will not clear itself. The underlying electrical fault or failed component must be repaired or replaced for the code to clear. You will need to clear the code with a scan tool after the repair.
How do I fix P0135 myself?
Start by checking the O2 sensor wiring and the relevant fuse. If they are good, test the O2 sensor heater circuit resistance with a multimeter. If it's out of spec, replace the Bank 1 Sensor 1 oxygen sensor.
How much does it cost to fix P0135?
DIY repair costs $50-$200 for a new O2 sensor and potentially an O2 sensor socket. Professional repair costs $150-$500, including parts and labor.
P0135 keeps coming back - why?
The code keeps returning if the root cause wasn't addressed. This could be a faulty new O2 sensor, a persistent wiring issue that wasn't fully repaired, or a rare PCM problem.
Will P0135 fail emissions/smog test?
Yes, P0135 will cause your vehicle to fail an emissions or smog test. The O2 sensor heater circuit must be functional for the emissions system to pass its self-tests.
What's the difference between P0135 and P0130?
P0135 specifically indicates a problem with the *heater circuit* of the Bank 1 Sensor 1 O2 sensor, meaning the sensor isn't getting hot enough. P0130 indicates a general *malfunction* in the sensor's circuit, which could be related to its signal output rather than just the heater.
P0135 on Honda Accord?
P0135 on Honda Accords (especially 2003-2012 models) is very commonly caused by a failed upstream O2 sensor. Replacing the sensor typically resolves the issue.
Questions to Ask Your Mechanic
Did you check the O2 sensor heater circuit fuse and wiring before condemning the sensor?
Good answer: Yes, I confirmed power and ground at the connector and checked the fuse. The sensor itself has an open circuit on the heater element.
What were the resistance readings for the O2 sensor heater circuit?
Good answer: The heater circuit showed infinite resistance, indicating an open circuit, which means the heater element is burned out.
Repair Cost Estimate
DIY Repair
Parts only
$50-$200
Shop Repair
Parts + labor
$150-$500
Save $100-$300 by doing it yourself
Difficulty
intermediate
Time
1-2 hours
Intermediate - requires basic electrical testing with a multimeter and potentially an O2 sensor specific socket, but is generally accessible.
Cost of Waiting
Ignoring P0135 means your engine runs rich, wasting fuel and increasing emissions. This can lead to premature failure of your catalytic converter, turning a $50-$200 O2 sensor job into a $800-$2,500 converter replacement.
While You're In There...
If you're removing exhaust components to access the O2 sensor, replacing old gaskets prevents exhaust leaks and ensures a proper seal.
Applying anti-seize to the new O2 sensor threads prevents it from seizing in the exhaust, making future removal much easier.
Tools You'll Need
- OBD-II Scan Tool
- Multimeter
- O2 Sensor Socket (7/8" or 22mm)
- Ratchet
- Wire Brush (for exhaust threads)
- Anti-seize compound
P0135 is a very common code, and in most cases, it's a straightforward fix involving replacing the oxygen sensor. Your engine will run much better and more efficiently afterward.
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Your Next Steps
Step 1: Visually inspect the O2 sensor wiring and connector for damage. Check the O2 sensor heater fuse.
Step 2: If wiring and fuse are good, use a multimeter to test the resistance of the O2 sensor's heater circuit. Compare to factory specifications.
Step 3: If the sensor's heater circuit is open or out of spec, you'll likely need a new Bank 1 Sensor 1 oxygen sensor.