Fuel and air code
P0191: Fuel rail pressure sensor reading off
How this range is built
| Part of the job | Low | High |
|---|---|---|
| Parts | $150 | $500 |
| Labor: 2 to 3.5 hours × $125 to $175 an hour | $250 | $613 |
| Fees: shop supplies, disposal, diagnostics | $0 | $30 |
| Total, rounded | $400 | $1,150 |
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 pump replacement. Which repair your car needs depends on a proper diagnosis.
The fuel rail pressure sensor reports the pressure feeding the injectors. The reading it sent does not fit what the engine is doing, such as being too high or low at idle or load. Either the sensor is wrong, or the real pressure is off because of a weak pump or a restriction.
- Safe to drive?
- Short trips only
- Most common cause
- Failing fuel pressure sensor
Short drives are okay if it runs normally; stop if it stalls or loses power.
What you may notice
- Hard starting
- Stalling
- Hesitation
- Rough idle
Common causes, most likely first
- Failing fuel pressure sensor
- Weak fuel pump
- Clogged filter
- Wiring fault
- Leaking injector
Check this first
Ask whether the shop compared the sensor reading to a real gauge reading at the fuel rail. That one test tells them whether the sensor is lying or the pump and filter are actually failing.
Other repairs that sometimes fix P0191
| Repair | Typical range, Boston |
|---|---|
| Fuel injector replacement (one injector) | $180 to $910 |
| Diagnostic scan (check engine light) | $60 to $290 |
| CAN bus wiring repair | $190 to $1,275 |
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).
P0191 questions
Is it the sensor or the pump?
A gauge test settles it. The sensor can read wrong while the pressure is fine, and a weak pump can show a true low reading. Shops should measure real pressure before replacing either one.
Is this common on direct-injection cars?
Yes. Direct-injection engines run much higher fuel pressure, so pumps and sensors take more stress. That is why these codes show up often on newer cars and why the parts cost more.
Can I fix it myself?
Fuel system work is risky because of the high pressure and the fire danger from spraying fuel. Leave it to a shop, which can relieve pressure safely and test the fix.
How much does it cost to fix P0191?
The most common fix, fuel pump replacement, has a typical range of $400 to $1,150 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
- P0087: Fuel pressure too low
- P0171: Engine getting too much air or too little fuel (bank 1)
- P0172: Engine getting too much fuel (bank 1)
- 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.