P0155
Fix within 1-2 weeksOxygen Sensor Heater Circuit Malfunction (Bank 2 Sensor 1)
Code P0155 means your Bank 2 Sensor 1 oxygen sensor's heater circuit has failed. Common causes: Bad O2 sensor (80%), wiring issues (15%), blown fuse (4%). Drivability: Yes, safe to drive, but fix within 1-2 weeks. Repair cost: $50-$200 DIY, $150-$500 professional.
Can I Drive With P0155?
Yes, safe to drive
No restrictions, but fix within 1-2 weeks to avoid long-term issues and wasted fuel.
Stop driving immediately if: Flashing Check Engine Light (indicates severe misfire, not typical for P0155 alone), significant power loss, or a strong rotten egg smell from the exhaust.
Symptoms of P0155
- 1Check Engine Light is on
- 2Reduced fuel economy
- 3Increased emissions
- 4Engine may run rough at startup (until sensor warms up from exhaust)
- 5Failed emissions test
Common Causes of P0155
Parts most likely causing this code, ranked by probability
The internal heating element of the oxygen sensor has an open or short circuit, preventing it from reaching operating temperature quickly.
80% of P0155 cases are fixed by replacing the oxygen sensor
Frayed, corroded, or disconnected wiring prevents power from reaching the oxygen sensor's heater circuit.
15% of P0155 cases are fixed by repairing wiring or connectors
A blown fuse interrupts the power supply to the oxygen sensor's heater circuit.
4% of P0155 cases are fixed by replacing a blown fuse
The engine control module is not properly controlling or powering the oxygen sensor's heater circuit.
1% of P0155 cases are fixed by repairing or replacing the PCM
Check These First (Before Buying Parts)
- Visually inspect the Bank 2 Sensor 1 oxygen sensor and its wiring for any obvious damage, fraying, or disconnected plugs.
- Locate and check the fuse for the oxygen sensor heater circuit in your vehicle's fuse box. A blown fuse is a quick and cheap fix.
How to Diagnose P0155
- 1Visually inspect the Bank 2 Sensor 1 oxygen sensor and its wiring for damage, corrosion, or loose connections.
- 2Check the fuse for the oxygen sensor heater circuit (consult your vehicle's service manual for location).
- 3Disconnect the oxygen sensor and use a multimeter to check the resistance of the heater circuit terminals on the sensor itself. Compare to factory specifications.
- 4With the key on, engine off, check for power and ground at the oxygen sensor connector (on the vehicle harness side) for the heater circuit wires.
- 5If the sensor and wiring check out, a professional diagnostic scan tool can monitor live data for the O2 sensor heater circuit.
P0155 on Popular Vehicles
Toyota Camry
2007-2024P0155 on Camry models often points directly to a failed Denso brand O2 sensor. The sensor can be difficult to access on V6 models.
85% fixed by replacing the oxygen sensor
Honda Accord
2003-2024Honda Accords frequently trigger P0155 due to the heater element failing in the upstream oxygen sensor on Bank 2. Access can be tight, especially on V6 engines.
80% fixed by replacing the oxygen sensor
Ford F-150
2004-2024P0155 is a very common code on F-150s, particularly with the 5.4L and 4.6L engines. The Bank 2 Sensor 1 is on the passenger side exhaust manifold and can be seized in the exhaust.
85% fixed by replacing the oxygen sensor
Frequently Asked Questions
What does P0155 mean?
P0155 indicates that the heater circuit for your Bank 2 Sensor 1 oxygen sensor is not functioning correctly. This sensor is located before the catalytic converter on the engine bank that does not contain cylinder #1.
Can I drive with P0155?
Yes, you can drive with P0155, but you should fix it within 1-2 weeks. Your vehicle will run less efficiently, consume more fuel, and produce higher emissions.
Will P0155 clear itself?
No, P0155 will not clear itself. The underlying electrical fault in the heater circuit requires diagnosis and repair before the code will clear.
How do I fix P0155 myself?
Start by visually inspecting the Bank 2 Sensor 1 wiring and checking the relevant fuse. If those are good, you will likely need to replace the oxygen sensor itself.
How much does it cost to fix P0155?
A DIY fix for P0155 typically costs $50-$200 for a new oxygen sensor. Professional repair at a shop will cost $150-$500, including parts and labor.
P0155 keeps coming back - why?
If P0155 returns after replacing the sensor, the issue is likely not the sensor itself. Recheck the wiring for damage, corrosion, or poor connections, and verify the fuse is good. A rare PCM fault could also be the cause.
Will P0155 fail emissions/smog test?
Yes, P0155 will cause your vehicle to fail an emissions or smog test. The check engine light will be on, and the emissions system will not be ready.
What's the difference between P0155 and P0135?
P0155 refers to the heater circuit malfunction for Bank 2 Sensor 1 (the side of the engine without cylinder #1). P0135 refers to the same heater circuit malfunction but for Bank 1 Sensor 1 (the side of the engine with cylinder #1).
P0155 on Ford F-150?
On many Ford F-150 models, P0155 is a common code indicating a failed Bank 2 Sensor 1 oxygen sensor. This sensor is often located on the passenger side exhaust manifold and can be seized in place.
Questions to Ask Your Mechanic
Did you check the resistance of the O2 sensor's heater circuit, and did you verify power and ground at the connector?
Good answer: Yes, I measured X ohms on the sensor, which is out of spec, and confirmed 12V power and good ground at the harness connector.
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 hand tools, an oxygen sensor socket, and a multimeter for proper diagnosis. Access to the sensor can sometimes be challenging.
Cost of Waiting
Ignoring P0155 leads to reduced fuel economy and increased emissions. Over time, the engine's fuel trim will be inaccurate, which can cause premature failure of your catalytic converter ($800-$2,500 repair). A $50-$200 O2 sensor replacement now prevents a much larger bill later.
While You're In There...
If you need to remove exhaust components for access, 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 manifold, making future replacement easier.
Tools You'll Need
- Oxygen sensor socket
- Ratchet
- Extension (various lengths)
- Multimeter
- Wire brush
- Penetrating oil
- Jack and jack stands (if needed for access)
P0155 is a common code that points to a specific electrical issue with an oxygen sensor. This is a very fixable problem, and addressing it will restore your vehicle's fuel efficiency and emissions performance.
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Your Next Steps
Step 1: Check the fuse for the O2 sensor heater circuit and visually inspect the sensor's wiring for damage.
Step 2: If the fuse and wiring are good, disconnect the Bank 2 Sensor 1 oxygen sensor and test the resistance of its heater element with a multimeter. If it's open or shorted, replace the sensor.
Step 3: If the sensor's heater resistance is within spec, check for power and ground at the vehicle's O2 sensor harness connector. If power or ground is missing, trace the wiring back to the PCM.