Fuel injectors spray a precise amount of fuel into each cylinder. When one clogs, leaks, or sticks, you get misfires, poor MPG, and a check engine light. Here are the 7 most common signs of a bad fuel injector and what replacement costs.
A clogged or dead injector produces a steady misfire on one cylinder - usually P0301-P0308 codes. The engine feels rough at idle and stumbles under load.
When one cylinder is leaning out from a partly clogged injector, the engine shakes at idle and can stall during long stops.
Leaking injectors dump extra fuel. MPG can drop 3-7 mpg, and the exhaust may smell strongly of unburned gas.
A leaking injector floods the cylinder while parked, so it is hard to crank back up. A stuck-shut injector can stall the engine at low RPM.
Most injector failures throw either an injector circuit code (P020x), a misfire code (P030x), or a fuel trim code (lean).
On port-injected engines you can sometimes spot wet spots around an injector body or smell raw fuel under the hood.
Excess unburned fuel can spike HC readings or trigger the catalytic converter to overheat, causing eventual cat damage and failed inspections.
Symptoms overlap between parts. Run through these top 3 confirming tests before spending money on parts:
Costs vary by vehicle make, model year, and parts quality. Always get a written estimate before authorizing work.
Port-injected engines are easier - pop off the fuel rail, swap injector, reinstall. Direct injection (GDI) injectors require more force, special seals, and often an intake manifold removal. Cleaning is sometimes a viable middle-ground.
Get a free, vehicle-specific check based on your exact symptoms. We'll tell you what's most likely wrong before you spend a dime on parts.
Get a Free Vehicle-Specific Check →Takes 60 seconds. No account needed. AI-powered diagnosis tailored to your year, make, and model.
If your scan tool shows one of these codes, you can confirm the diagnosis. Click for full code details, common causes, and repair guidance.
On a high-mile engine, replacing all of them together avoids a repeat shop visit. On a low-mile engine, replacing just the failed one is fine.
It can help with mild clogging and gummed-up tips, especially in the first 100,000 miles. It will not fix a stuck plunger or electrical failure.
Typically 100,000 to 200,000 miles. Direct-injection (GDI) injectors tend to fail earlier due to higher pressures and carbon buildup.
Short trips, yes. A persistent misfire can ruin your catalytic converter and damage piston rings if it goes on for weeks.
Port injectors spray into the intake runner; direct injectors spray into the combustion chamber at very high pressure. GDI injectors cost more and are harder to replace.
Use top-tier gasoline, change fuel filter on schedule, and run a quality injector cleaner every 15,000 to 30,000 miles.