P0155 OBD-II Trouble Code: 02 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)

Our certified mechanics come to you · Get a fair and transparent estimate upfront

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0155 code

P0155 is a diagnostic trouble code (DTC) for "02 Sensor Heater Circuit Malfunction (Bank 2, Sensor 1)". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic for $114.99 . Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.0 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

Cars Estimate Credit towards follow-up repair Earliest Availability
Ford $114.99 $20.0
Toyota $114.99 $20.0
BMW $124.99 $20.0
SCHEDULE P0155 DIAGNOSTIC Get a fair and transparent estimate upfront

P0155 trouble code definition

O2 Oxygen Sensor Heater Circuit Malfunction (bank 2 sensor 1)

What the P0155 code means

When the P0155 code is present, it is an indication that the heater element of the oxygen sensor is taking longer than the normal to heat up. The power control module (PCM) will store the P0155 trouble code and the Check Engine Light will come on to alert the vehicle’s operator to the problem.

What causes the P0155 code?

  • The oxygen sensor (bank 2 sensor 1) not working properly
  • A broken or bare wire leading to the oxygen sensor
  • A fuse to the circuit for the oxygen sensor has blown
  • The engine coolant temperature sensor not working as it should
  • The power control module (PCM) is defective (much less likely)

What are the symptoms of the P0155 code?

  • The Check Engine Light is illuminated
  • The vehicle is running rough
  • The vehicle is consuming more fuel than usual
  • The vehicle is shutting off occasionally
  • There is a rotten egg smell coming from the exhaust
  • There is black smoke coming out of the exhaust

Some or all of these symptoms may be present with the P0155 trouble code.

How does a mechanic diagnose the P0155 code?

In most cases, the presence of this code indicates that the oxygen sensor needs to be replaced. Before doing so, the following steps should be taken:

  • Use an OBD-II scanner to collect the trouble codes that have been stored by the power control module (PCM).

  • Visually inspect the wiring that leads to the oxygen sensor for breaks in the wires or bare wires.

  • Use the OBD-II scanner to view live data in order to make sure the oxygen sensor is working properly.

  • If the coolant temperature sensor is not operating properly, the power control module (PCM) will store this code as well, so this should be inspected and tested as well.

  • In rare cases, the power control module (PCM) may be defective and this would require advanced diagnosis to make a determination as to whether this is the problem. This should be considered last, and only after every other possible attempt at repair has failed.

Common mistakes when diagnosing the P0155 code

  • Replacing the oxygen sensor before inspecting the other components

  • Not inspecting the wires leading to the oxygen sensor for breaks and/or bare wires before the oxygen sensor is replaced

How serious is the P0155 code?

The P0155 trouble code is considered to be a moderately serious code. The reason for this is that drivability problems and poor fuel consumption is possible when this trouble code is present.

What repairs can fix the P0155 code?

Additional comments for consideration regarding the P0155 code

The removal of the oxygen sensor can be difficult if you do not have an oxygen sensor set and propane tank. The oxygen sensor can be difficult to reach, depending on the vehicle. If the oxygen sensor has ceased in the exhaust, which is common, a heating element will be required to remove it.

Need help with a P0155 code?

YourMechanic offers certified mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

Check Engine Light
P0155
trouble codes

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0155 code.

SCHEDULE P0155 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating

(7400)

Rating Summary
6879
249
58
41
173
6879
249
58
41
173
 at YourMechanic

David

13 years of experience
393 reviews
David
13 years of experience
Chevrolet Malibu L4-2.4L - Check Engine Light is on Inspection - Marietta, Georgia
He explained everything to me in detail on what I needed to know about my car. Definitely recommend him for getting the job done.
 at YourMechanic

Raymond

37 years of experience
402 reviews
Raymond
37 years of experience
Toyota Camry L4-2.2L - Check Engine Light is on - Las Vegas, Nevada
Raymond did a great job however I was charged for two hours labor and he was only here less than 45 minutes. should I expect this on future appointments with your mechanic ?
 at YourMechanic

Shane

17 years of experience
217 reviews
Shane
17 years of experience
Volkswagen EuroVan V6-2.8L - Check Engine Light is on Inspection - Austin, Texas
Arrived on time. Explained the issues he found and how he will fix it. I have parts on order and will schedule an appointment to have Shane install the parts when they arrive.
 at YourMechanic

Kanstantsin

19 years of experience
51 reviews
Kanstantsin
19 years of experience
Ford F-150 V8-4.6L - Check Engine Light is on Inspection - Littleton, Colorado
Kanstantsin arrived early. Was very courteous and professional. Will highly recommend to anyone. Thank you Kanstantsin.


Related questions

Getting multiple codes
Hello. When you get these codes together it is typically the result of a vacuum leak. If there is too much air entering the engine, your truck will have idling problems and this will cause issues with the oxygen sensor...
Po155cnf bank 2 sensor heater circuit P1620cnf Also code
The P0155 (https://www.yourmechanic.com/article/p0155-obd-ii-trouble-code-02-sensor-heater-circuit-malfunction-bank-2-sensor-1-by-jamahl-walker) is the oxygen sensor located on the rear bank of cylinders and before the catalytic converter. Given your mileage, both oxygen sensors (https://www.yourmechanic.com/services/oxygen-sensor-replacement) (pre-catalytic converter) should be replaced. The pre-cat sensors have the most affect on fuel...
Periodically vehicle runs rough at idle.
Hi there. Most of the codes that are coming on are for a misfire on cylinder number 3. Check the spark plug and wire on cylinder 3 and see if you are getting a good spark. Then check the fuel...

More related articles

P2100 OBD-II Trouble Code: Throttle Actuator Control Motor Circuit Open (TACM)
P2100 code definition Throttle Actuator Control Motor Circuit Open (TACM) What the P2100 code means P2100 is an OBD-II generic code which...
P2147 OBD-II Trouble Code: Malfunction with the Fuel Injector Group A Supply Voltage Circuit Low
P2147 P2147 code definition P2147 is a generic OBD-II diagnostic trouble code indicating a malfunction with the fuel injector group A supply voltage circuit low. What the P2147 code means The P2147 code means than the fuel injector group A...
P3429 OBD-11 Trouble Code: Cylinder Exhaust Valve Control Circuit/Open
What What the P3429 code means This code indicates that there is a problem with the exhaust valve on cylinder number 4. Your vehicle’s control module detects that the measured values from the MAP sensor, MAF sensor, and TP sensor...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com