Emissions code
P2270: Downstream oxygen sensor stuck lean (bank 1)
How much to fix P2270? 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 behind the catalytic converter on cylinder 1's bank is stuck reading lean and not swinging the way it should. This sensor checks whether the converter is working, so a stuck one can make the computer wrongly doubt the converter or set other codes.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Worn downstream O2 sensor
Safe to drive. It mainly affects emissions.
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What you may notice
- Check-engine light on
- No change in how the car drives
- May fail the emissions readiness check
Common causes, most likely first
- Worn downstream O2 sensor
- Exhaust leak
- Wiring issue
- Converter problem
Check this first
Ask for an exhaust leak check at the joints in front of the sensor. Extra air leaking in at those joints can make the rear sensor read lean, and fixing the leak is much cheaper than replacing a sensor or a converter.
Other repairs that sometimes fix P2270
| Repair | Typical range, US |
|---|---|
| Catalytic converter replacement | $430 to $2,325 |
| 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).
P2270 questions
Does it hurt anything?
It can lead to a failed inspection because the light stays on, but it does not damage the engine. The risk is in ignoring it long enough that another problem develops unnoticed.
Should I replace the converter?
Only if tests show it is failing. Compare the front and rear sensor readings first. If the front sensor swings and the rear stays flat, the converter is working well.
Will it return?
A new sensor usually fixes it, as long as no leak or wiring problem caused the stuck reading. If the code returns soon after, ask the shop to recheck the wiring and exhaust.
How much does it cost to fix P2270?
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
- P0137: Rear oxygen sensor reads low (bank 1, after converter)
- P0138: Rear oxygen sensor reads high (bank 1, after converter)
- P0420: Catalytic converter not working well (bank 1)
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.