Fuel and air code
P0171: Engine getting too much air or too little fuel (bank 1)
The computer keeps adding extra fuel to make up for something, and it has reached its limit on the side with cylinder 1. This is called running lean, and it usually means unmetered air is sneaking in or fuel is not getting through.
- Safe to drive?
- Usually yes, for now
- Most common cause
- Cracked vacuum hose or leaking intake gasket
You can usually drive it for a short while, but a lean engine can run hot and stumble, so fix it soon and stop if it hesitates badly.
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $5 | $60 |
| Labor: 0.8 to 2.5 hours × $125 to $175 an hour | $100 | $438 |
| Fees: shop supplies, disposal, diagnostics | $0 | $25 |
| Total, rounded | $100 | $530 |
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, vacuum leak repair. Which repair your car needs depends on a proper diagnosis.
What you may notice
- Rough idle
- Hesitation when you press the gas
- Poor mileage
Common causes, most likely first
- Cracked vacuum hose or leaking intake gasket
- Dirty or failing mass airflow sensor
- Weak fuel pump or clogged fuel filter
- Leaking fuel injector or low fuel pressure
- Exhaust leak ahead of the oxygen sensor
Check this first
Listen for a hissing sound with the engine running and look for cracked hoses or a loose air-intake tube. A can of mass-airflow cleaner is a cheap first try.
Other repairs that sometimes fix P0171
| Repair | Typical range, Boston |
|---|---|
| Mass airflow sensor replacement | $130 to $410 |
| Fuel pump replacement | $400 to $1,150 |
| Fuel injector replacement (one injector) | $180 to $910 |
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).
P0171 questions
What is a lean code?
It means the mix has too much air compared to fuel. The computer sees it in the oxygen sensor readings.
Is it okay to clean the MAF sensor myself?
Yes, with a spray made for that sensor, and only when the engine is off. Do not touch the delicate wires.
Why did it show up after an air filter or oil change?
A loose intake tube or unplugged sensor connector from that work can let extra air in. Check that everything is clipped back on.
How much does it cost to fix P0171?
The most common fix, vacuum leak repair, has a typical range of $100 to $530 in Boston. It is an estimate built from parts prices and local labor wages, not a quote. Your car and shop change it.
P0171 repair cost by city
Related codes
- P0174: Engine getting too much air or too little fuel (bank 2)
- P0172: Engine getting too much 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.