P0055 OBD-II Trouble Code: Heater Circuit Resistance (Bank 1, Sensor 3)

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

Red-stars EXCELLENT RATING ON

Cost of diagnosing the P0055 code

P0055 is a diagnostic trouble code (DTC) for "Heater Circuit Resistance (Bank 1, Sensor 3)". 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. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 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$20.00
Toyota$20.00
BMW$20.00
SCHEDULE P0055 DIAGNOSTIC Get a fair and transparent estimate upfront

P0055 code definition

Heater Circuit Resistance (Bank 1, Sensor 3)

What the P0055 code means

When this code is set it means that the Engine Control Module (ECM) has detected a problem with the amount of resistance in the heater circuit for the third oxygen sensor on bank one of the engine.

What causes the P0055 code?

The most common cause for this code is the heater inside the oxygen sensor burning out. When this happens, it will cause the circuit to either incomplete, or open, or short out. Essentially, the ECM has a preset amount of resistance that it wants to see for the sensor to heat up properly.

When the circuit is open, there will be an infinite amount of resistance because current can no longer travel along a complete path. When the sensor shorts out, the resistance is too low and the sensor will not heat up enough for the sensor to operate properly.

What are some of the symptoms of the P0055 code?

There are no perceptible symptoms for a P0055. The only symptom of P0055 is that the sensor will not begin operating correctly until the exhaust has heated it up sufficiently, as opposed to the built-in heater heating it up. This could cause an increase in emissions, which is why the Check Engine Light is illuminated.

How does a mechanic diagnose the P0055 code?

The diagnosis starts with a visual inspection of the sensor and its associated wiring. Besides a failed sensor heater, the most common issue that causes this code is damaged wiring or connectors. The damage could be caused by rubbing on body components, or from road hazards.

Once the visual inspection is completed, the next step is to measure the resistance of the heater in the oxygen sensor. This is done by unplugging the connector for the oxygen sensor and using a multimeter to measure the resistance, measured in ohms, across the heater terminals. The service manual will have a specification for a known good sensor. If the reading is out of specification, then the sensor will need to be replaced.

If the sensor is good, the next step is to measure the resistance of the wiring from the ECM to the oxygen sensor plug. Usually, you never have to go this far because the sensor is almost always at fault. Generally, you'd like to see the resistance of the wiring to be less than half an ohm.

If that checks out, the most likely culprit lies within the Engine Control Module itself. The ECM usually activates and grounds the heater circuit. There can be problems in the circuit; the contacts in the ECM may get burned and cause a higher than normal resistance reading. This would definitely cause the P0055 code to set.

Common mistakes when diagnosing the P0055 code

  • Not properly performing tests and diagnostics

As stated earlier, the sensor itself is often the problem. Often times a mechanic may just replace the sensor without any diagnostics, which isn't always the best path to repair.

How serious is the P0055 code?

Generally this code is not very serious. However, there is a very slight chance that a problem in the heater circuit could burn the contacts in the Engine Control Module. Replacing an ECM can be quite costly.

What repairs can fix the P0055 code?

Need help with a P0055 code?

YourMechanic offers certified mobile 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.

P0055
trouble codes
Check Engine Light

No more waiting rooms! Our mechanics will come to you to diagnose and fix the P0055 code.

SCHEDULE P0055 DIAGNOSTIC
Get a $20 credit for the follow-up repair

Recent Check Engine Light is on Inspection reviews

Excellent Rating


YourMechanic Check Engine Light is on Inspection Service

Average Rating

4.8/5

Number of Reviews

5,170

Rating Summary
4,765
197
50
27
131
4,765
197
50
27
131

Fred

16 years of experience
364 reviews
Fred
16 years of experience
Mercedes-Benz E500 - Check Engine Light is on - Conroe, Texas
Fred was very friendly and thorough to get to the root of the issue. Even when he could not find a fault to why my engine light was on, he went above and beyond to make absolutely sure that the concern was minimized. Turns out, all that needed to be done was a reset but his diagnostic to address my issues was very intricate and appreciated.

David

17 years of experience
37 reviews
David
17 years of experience
Chevrolet Cruze - Check Engine Light is on - Aurora, Colorado
David was on time, professionalisms & honest! I would definitely request him again and pass along to friends/family.

John

18 years of experience
18 reviews
John
18 years of experience
Dodge Ram 1500 - Check Engine Light is on - Memphis, Tennessee
Demonstrated good integrity. Advised me when work I thought needed done was unnecessary and was helpful in identifying issues that needed to be addressed

Robert

21 years of experience
17 reviews
Robert
21 years of experience
Chrysler 200 - Check Engine Light is on - Fort Worth, Texas
Robert did a good job working on my car and letting me know what's needed to keep my car driving smoothly.


More related articles

P3468 OBD-11 Trouble Code: Cylinder 9 Deactivation/Intake Valve Control Circuit High
What What the P3468 code means This code indicates that there is a problem with the intake valve on cylinder number 9. When your vehicle’s powertrain control module (PCM) notices that the measured values of the mass airflow sensor, the...
B1250 OBD-II Trouble Code: Air Temperature Internal Sensor Circuit Failure
B1250 means there is an error with the air temperature internal sensor, mostly caused by a defective sensor or damaged electrical components.
P2134 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch F Circuit Intermittent
What What the P2134 code means? P2134 is an OBD-II generic code for the engine control module (ECM) detecting the throttle pedal position sensor F has an intermittent sensor return to the ECM What causes the P2134 code? The...

Related questions

The Check Engine light blinks and the car stalls. Is this my catalytic converter?

This may be related to many different things such as a bad oxygen sensor (this monitors the activity of the catalytic converter), a bad or dirty idle air control valve, or potentially low fuel pressure. The low fuel pressure will...

Car reads "Pressure Control Valve 3V". I believe it has to do with a solenoid.

Hello. I would need to know some more information about what you car is doing to be able to help with a diagnosis. If it is giving a pressure control code then most of the time this is caused by...

I'm having problems with code po740

Hi there. In order to be able to give you more exact information I would need to know whether or not the vehicle is equipped with the CVT transmission. It sounds like you have the regular transmission in your vehicle....

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