Emissions code
P0136: Downstream oxygen sensor circuit problem (bank 1)
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $40 | $180 |
| Labor: 0.6 to 1 hours × $125 to $175 an hour | $75 | $175 |
| Fees: shop supplies, disposal, diagnostics | $0 | $15 |
| Total, rounded | $110 | $370 |
The hourly rate is the BLS Occupational Employment and Wage Statistics, May 2025 average pay for this trade in Boston, $31.54 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 not giving a normal electrical signal. This sensor checks whether the converter is cleaning the exhaust. A sensor fault here can set off a false converter code, so it should be sorted out first.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Failed downstream O2 sensor
Does not affect drivability, so you can keep driving. The light will stay on and will fail emissions inspection.
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
- Failed downstream O2 sensor
- Damaged wiring or connector from exhaust heat
- Exhaust leak near the sensor
- Stuck or corroded plug
Check this first
Check the wiring near the exhaust for melted insulation. Ask if the code appears with other O2 codes.
Other repairs that sometimes fix P0136
| Repair | Typical range, Boston |
|---|---|
| Diagnostic scan (check engine light) | $60 to $290 |
| Catalytic converter replacement | $400 to $1,900 |
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. Massachusetts rules 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).
P0136 questions
Does this mean my converter is bad?
Not by itself. The sensor is checked first, since a bad sensor can look like a failing converter. Replacing a converter based on this code alone could waste a lot of money.
Can I replace one sensor?
Yes, the one named in the code. On older cars, some shops recommend replacing them as a pair, but the other sensor may be fine, so ask what its live readings show before agreeing.
Why is the sensor stuck?
Exhaust heat and age wear down both the wiring and the sensing element. Wires run close to hot pipes, and insulation can crack or melt, which causes circuit faults like this one.
How much does it cost to fix P0136?
The most common fix, oxygen sensor replacement (one sensor), has a typical range of $110 to $370 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
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.