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 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 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.

Check Engine Light
P0055
trouble codes

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

(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.


More related articles

P0524 OBD-II Trouble Code: Engine Oil Pressure Too Low
P0524 means there is an abnormally low oil pressure reading often due to defective engine components or incorrect oil viscosity.
P0755 OBD-II Trouble Code: Shift Solenoid B Malfunction
P0755 code means that there is a problem with the the shift solenoid B due to transmission failure, low or dirty fluid, or a faulty solenoid.
P0298 OBD-II Trouble Code: Engine Oil Over Temperature Condition
P0298 means that the engine is or has recently overheated due to low coolant level, faulty cooling fan, thermostat, or radiator.

Related questions

Car idling and running rough
Hello, the engine is equipped with an electronic valve called an idle air control valve. The idle air control valve lets a metered amount of air into the engine at idle to have a comfortable idle and ensure the engine...
Check engine light on high idle low power
You may have to replace the magnetic cam actuator for the exhaust cam. The actuator comes in the front assembly. The actuator controls the cam with the magnetic clutch. You should also make sure you are using the correct weight...
P0604 code pops up. Check engine light is on and p2107 p2110 and u0100
Hi there. The code U0100 (https://www.obd-codes.com/u0100) means that the ECM (computer) has lost communication. Check the battery and the battery cables and make sure that they are in good condition. Check the ground wires to the chassis and to the...

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