Diesel injectors fire at 30,000+ PSI and live a brutal life. Stuck-open injectors flood cylinders, stuck-closed injectors cause misfires, and leaking injectors dilute oil with fuel. A single bad injector can cost $400-$900 - a full set can run $3,000-$5,000.
A stuck-open injector can dilute the crankcase with diesel fuel. In severe cases the engine consumes its own oil and runs uncontrollably. If you see rising oil level on the dipstick that smells of fuel, stop driving.
A leaking injector bleeds rail pressure during the hot soak. You crank longer than usual after a 30-minute shutdown. Test rail pressure during crank with a scan tool.
View P0201 Diagnosis →A scan tool will show balance rates / contribution values. A cylinder reading +5 to +9 mg is starving (clogged injector), -5 to -9 mg is overfueling (stuck open).
View P0300 Diagnosis →White smoke = unburned fuel from a clogged or weak injector. Black smoke = overfueling from a stuck-open injector. Both indicate replacement.
Get a free diagnosis →A severely leaking injector dumps fuel past the rings into the crankcase. Oil level rises above the dipstick max mark. Stop driving - engine runaway risk.
Get a free diagnosis →Worn injectors with poor spray pattern cause uneven combustion and louder-than-normal knock. Use a stethoscope at each injector to find the loudest.
Get a free diagnosis →A stuck-rich injector burns 10-25% more fuel. Sudden MPG drop with no other obvious cause - check injector balance rates first.
Get a free diagnosis →Run a free AI diagnosis tailored to your exact diesel. Get the most likely cause in under 30 seconds.
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Ford TSB 09-1-7 covers FICM-related injector misdiagnosis on 6.0L Powerstroke. GM TSB 06-06-04-070 updates LBZ Duramax injector replacement procedures. Ram TSB 18-019-19 covers 5.9L and 6.7L Cummins injector copper washer torque sequence. Ford's CP4 bypass on 6.7L Powerstroke saves $10,000+ injector damage from pump failure.
If you see a check engine light, these codes most often relate to the issues above. Click any code for full diagnosis steps.
150,000-300,000 miles in modern common-rail diesels. Contaminated fuel cuts that drastically.
Single replacement is fine for most diesels, but if one fails near 200K miles, the others are usually close behind. Many shops recommend a full set.
$400-$900 per injector parts and labor. Full set on a V8 diesel: $3,000-$5,000. Cummins straight-six: $2,500-$4,000.
No on most modern common-rail diesels - injectors come out from the top. Some Cummins ISB engines require valve cover and rocker removal only.
HEUI (6.0L Powerstroke) uses high-pressure engine oil to fire. Common-rail (every modern diesel) uses electronic solenoids and 30,000+ PSI fuel.
Crack each injector return line one at a time. The cylinder with the smallest fuel return is likely the bad one. Better: scan tool injector balance test.