OBD-II trouble code
P0055: HO2S Heater Resistance (Bank 1, Sensor 3)
SAE J2012: HO2S heater resistance, bank 1 sensor 3. Sensor 3 is the third sensor in airflow order. The 2005 3.8L file publishes resistance windows for sensors 1 and 2 only. The 2014 Golf CBUA section prints heater-circuit rows for sensor 3, not a resistance limit for P0055.
Quick facts
- System
- Powertrain
- Category
- Oxygen Sensor
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $300 – $580 (oxygen sensor replacement, parts and labor)
- DIY difficulty
- Intermediate DIY
Browse every code in P0001–P0099, or start from the full code library.
What does P0055 mean?
SAE J2012 APR2002 names P0055 HO2S Heater Resistance, Bank 1 Sensor 3. The title is resistance. P0042, P0043, and P0044 are the circuit, circuit-low, and circuit-high codes for the same sensor number. Section 3.6 counts sensors in the order air and exhaust pass them. Sensor 3 is the third. Figures 1 through 3 draw a third heated sensor farther along the pipe on those example engines. A diagram that stops at two sensors is not a vehicle this code describes.
Bank 1 is the bank that contains cylinder 1. On a single-bank engine, sensor 3 is the third sensor on that one exhaust, not a second bank.
The 2005 GM 3.8L (L26) with AIR mode-6 file fails P0053 when calculated resistance is outside 3.13 to 9.3 ohms, and P0054 when it is outside 8.82 to 22.17 ohms. Both enables are a cold start after a soak longer than 10 hours. The pages read do not contain a P0055 row. Those two windows are the wrong numbers for sensor 3, and they are the wrong numbers on any engine that is not that file.
The 2014 Volkswagen Golf, GTI, and Golf R Quick Reference Specification Book (NHTSA MC-10122269), engines CBTA and CBUA, prints P0042, P0043, and P0044 as heater-circuit rows and marks them CBUA only. No resistance limit for P0055 was on those rows. The voltage cells in the extract do not stay with the code names, so none are repeated. CBUA is not a repair for every Golf, and a circuit row is not a resistance spec.
A hot ohmmeter reading is not a cold-start calculation. Where this calibration prints an enable, use that enable. Where it does not, the pass/fail number is the one in this vehicle's procedure, not a number borrowed from sensor 1 or sensor 2.
Harness resistance in series with the element moves a calculated value. Check the supply and the low-control side for voltage drop with the heater commanded, using the steps this sensor 3 chart prints. Do not paste the 2006 GM sensor 1 step numbers onto sensor 3.
Common causes
- A calculated sensor 3 heater resistance outside the window this calibration prints
- The 3.13 to 9.3 ohm or 8.82 to 22.17 ohm window from the 2005 3.8L file used on sensor 3
- The CBUA heater-circuit rows used as if they were a resistance limit
- Voltage drop in the sensor 3 heater supply or low-control wire while the heater is commanded
- A replacement sensor 3 whose heater is not the resistance this calibration calculates
- A vehicle with two oxygen sensors diagnosed as if a third sensor were on the pipe
Symptoms
- Check engine light with P0055
- No third oxygen sensor on the diagram, which means the code and the calibration need a second look before a part is ordered
- P0042, P0043, or P0044 stored beside it on a calibration that separates the circuit codes from the resistance code
- A new rear sensor setting the code because its heater resistance is not the one this monitor calculates
- The code returning after a hot-bay resistance check that never ran the published enable
- An inspection held up by the stored code or by a monitor that needs this heater
Diagnostic steps
- 1.Count sensors on this vehicle's exhaust diagram, from the engine toward the tailpipe. Sensor 3 is the third on bank 1. If the diagram has two, stop and confirm the code before you order a sensor.
- 2.Do not use 3.13 to 9.3 ohms or 8.82 to 22.17 ohms. Those are P0053 and P0054 on the 2005 3.8L L26 with AIR. The pages read of that file do not define P0055.
- 3.On a 2014 Golf, the CBTA/CBUA section of the January 2014 specification book (MC-10122269) is a heater-circuit section for sensor 3, marked CBUA only. It is not a P0055 resistance limit, and it is not for CCTA, CBFA, CJAA, or CRZA.
- 4.Read the enable this procedure prints. If it is a cold-start calculation, a reading on a warm lift is a different test. Compare a meter reading only with a spec that says it is a cold-sensor measurement.
- 5.With the heater commanded, measure voltage drop on the supply and on the low-control wire to the limits this sensor 3 chart prints. An unpowered continuity check can miss the drop that moves the calculation.
- 6.Replace sensor 3 when the harness drop is inside the printed limits and the element is not. Repair the wire when the drop is in the wire. Do not replace a catalytic converter from a heater-resistance code.
- 7.Clear P0055 and complete the enable the chart names. A hot retest does not run a cold-start monitor.
Repair cost
$300 – $580 (oxygen sensor replacement, parts and labor)
RepairPal has one oxygen-sensor job and does not publish a sensor-3 price. Updated 3 September 2026: average $440–$523, labor $93–$136, parts $347–$387, taxes and fees excluded. Near-me examples: Honda Civic $479–$522, Toyota Corolla $500–$570, Honda Accord $483–$529, Chevrolet Silverado 1500 $306–$407. Printed pair $300–$580 is that sensor job. A connector, a harness drop, or a fuse is outside it. RepairPal's page says the vehicle is lifted for the job. Use stands or a lift, keep the exhaust cool, and keep an open flame away from fuel and undercoating.
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DIY vs shop
This is an intermediate DIY job. It usually involves diagnostic steps, specialty parts, and some careful work in tight spaces. If you have the tools and a service manual or trustworthy video for your specific vehicle, it is achievable in a weekend. Otherwise, a competent independent shop will be faster.