Emissions code
P0155: Upstream oxygen sensor heater circuit problem (bank 2)
How much to fix P0155? Typically $100–$350.
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $40 | $180 |
| Labor: 0.6 to 1 hours × $110 to $150 an hour | $66 | $150 |
| Fees: shop supplies, disposal, diagnostics | $0 | $15 |
| Total, rounded | $100 | $350 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in the US, $27.13 an hour, times 4 to 5.5 to cover what a shop bills (overhead, tools, insurance, profit). Parts are a band from budget aftermarket to the manufacturer part. Full method.
Not a repair shop, estimates only. Typical range, estimate. Not a quote. Your car, parts and shop change the number.
This is the range for the most common fix, oxygen sensor replacement (one sensor). Which repair your car needs depends on a proper diagnosis.
The oxygen sensor in front of the catalytic converter on the side without cylinder 1 has a built-in heater. The computer found that heater's circuit is not working, so the sensor warms up slowly, which makes cold starts less clean and hurts fuel economy for the first few minutes.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Failed O2 sensor heater
Safe to drive. Mileage and cold-start emissions may suffer.
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What you may notice
- Lower fuel economy
- Rough cold start
- Check-engine light
Common causes, most likely first
- Failed O2 sensor heater
- Blown fuse
- Wiring or connector fault
- Bad relay
Check this first
Find the fuse for the oxygen sensor heater and check whether it is blown. Then look at the sensor plug for corrosion. A fuse or loose plug is much cheaper to fix than a new sensor, so rule them out first.
Other repairs that sometimes fix P0155
| Repair | Typical range, US |
|---|---|
| Diagnostic scan (check engine light) | $55 to $250 |
Before you pay
- Ask the shop what test showed this part is the cause, not just that the code appeared.
- Ask for parts and labor listed separately, and for the hours.
- Ask for a written OK before any extra work. Many states require written authorization before repairs.
Got a quote already? Check it against the range. Want to see if your car has a recall tied to this problem? Check recalls by VIN.
Need to read a code yourself? OBD-II scanners on eBay (affiliate link, disclosure).
P0155 questions
What does the heater do?
It warms the sensor to working temperature in seconds so the computer can control fuel soon after a start. Without it, the sensor takes minutes, and the engine runs richer during that time.
Can I clean the sensor?
No. The heater is a built-in electrical element, and a fault there cannot be cleaned away. The sensor is replaced as a single part, and it is a regular wear item on most cars.
Will it pass inspection?
Not while the light is on. Most inspection programs fail a car with an active check-engine light, and many also reject cars whose emissions tests have not run since the last repair.
How much does it cost to fix P0155?
The most common fix, oxygen sensor replacement (one sensor), has a typical range of $100 to $350 across the US. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
Typical range in 10 metro areas
Only the labor rate changes between cities. Same parts, same hours.
| Area | Typical range, estimate |
|---|---|
| Boston area, Massachusetts | $110 to $370 |
| New York City area | $110 to $360 |
| Los Angeles area, California | $110 to $370 |
| Chicago area, Illinois | $100 to $350 |
| Houston area, Texas | $100 to $340 |
| Dallas-Fort Worth area, Texas | $100 to $340 |
| Phoenix area, Arizona | $100 to $350 |
| Atlanta area, Georgia | $100 to $350 |
| Miami area, Florida | $100 to $350 |
| Seattle area, Washington | $110 to $370 |
Related codes
- P0135: Oxygen sensor heater fault (bank 1, before converter)
- P0141: Oxygen sensor heater fault (bank 1, after converter)
- P0161: Oxygen sensor heater fault (bank 2, after converter)
More emissions codes
Code meaning written in our own words. Some codes mean different things on different makes, so check your scan tool or manual. Not a repair shop, estimates only.