Fuel and air code
P0172: Engine getting too much fuel (bank 1)
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $50 | $260 |
| Labor: 1 to 3.5 hours × $125 to $175 an hour | $125 | $613 |
| Fees: shop supplies, disposal, diagnostics | $10 | $30 |
| Total, rounded | $180 | $910 |
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, fuel injector replacement (one injector). Which repair your car needs depends on a proper diagnosis.
The oxygen sensors on the side of the engine with cylinder 1 are reporting too much fuel for the amount of air. The computer is already trimming fuel back as far as it can and the mix is still too rich, which wastes gas and can overheat the catalytic converter over time.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Leaking or stuck-open fuel injector
Safe for short trips, but a rich engine wastes gas and can foul the converter, so get it looked at soon.
What you may notice
- Black smoke or fuel smell from the tailpipe
- Poor mileage
- Rough idle
Common causes, most likely first
- Leaking or stuck-open fuel injector
- Dirty or failing mass airflow sensor
- Bad oxygen sensor
- Clogged air filter
- High fuel pressure from a bad regulator
Check this first
Check the engine air filter and look for a fuel smell in the oil. Ask the shop to check fuel pressure and look at the fuel trim numbers.
Other repairs that sometimes fix P0172
| Repair | Typical range, Boston |
|---|---|
| Mass airflow sensor replacement | $130 to $410 |
| Oxygen sensor replacement (one sensor) | $110 to $370 |
| Diagnostic scan (check engine light) | $60 to $290 |
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).
P0172 questions
Can a dirty air filter set this code?
It can, when it is badly clogged and starving the engine of air. A new filter is cheap, so it is an easy thing to rule out first. If the filter is already clean, the cause lies elsewhere.
Is a rich engine bad for the catalytic converter?
Yes, over a long time. Unburned fuel overheats and coats the converter, which can ruin it. So do not let a rich code sit for months. Addressing it early costs far less than a new converter.
Can oil smell like gasoline with this?
Yes. A leaking injector can wash fuel into the crankcase and thin the oil. If the oil smells like gasoline or the dipstick reads over full, change the oil soon and ask the shop to test the injectors.
How much does it cost to fix P0172?
The most common fix, fuel injector replacement (one injector), has a typical range of $180 to $910 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
P0172 repair cost by city
Related codes
- P0175: Engine getting too much fuel (bank 2)
- P0171: Engine getting too much air or too little fuel (bank 1)
- P0101: Air flow sensor reading seems off
- P0300: Random or multiple cylinder misfires
More fuel and air 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.