Fuel Injector
What it is
A fuel injector is an electronically controlled nozzle that sprays a precise amount of fuel into each cylinder (or intake port). There is one per cylinder.
What it does
It atomises fuel for clean, efficient combustion. A clogged injector causes a lean misfire on that cylinder; a leaking injector causes a rich condition and rough running — both can show up as misfire codes (P0301–P0304) or a rich code (P0172).
Symptoms of failure
- Cylinder misfire codes (P0301–P0304) or rich code P0172
- Rough idle and hesitation
- Poor fuel economy or fuel smell
- Hard starting
- Failed emissions test
Common fault codes
Which vehicles need it
All fuel-injected engines. Direct-injection engines are more prone to deposits and can need periodic cleaning.
Replacement cost
| DIY (part only) | $30–$250 |
|---|---|
| At a shop (parts + labor) | $200–$800 |
| Replacement interval | No set interval — clean with a good fuel-system cleaner; replace a failed injector. |
| DIY difficulty | Moderate (DIY) — accessible on port-injection engines; direct-injection is harder |
| Recommended brands | Bosch, Denso, Delphi, OEM |
Where to buy the part
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Frequently asked questions
Can a fuel injector cause a misfire?
Yes. A clogged injector starves its cylinder and causes a lean misfire; a leaking one floods it. A cylinder-specific misfire code (e.g. P0302) that does not follow a coil or plug swap points to the injector.
Will fuel injector cleaner fix a clogged injector?
A quality fuel-system cleaner can clear light deposits and is a cheap first step. A physically failed or badly clogged injector needs professional cleaning or replacement.