What does P0093 mean?
The computer saw rail pressure drop much faster than fuel delivery explains, and decided fuel is leaking from the high-pressure system.
Codes are a starting point. They tell you which test failed, not which part to replace. Check for other stored codes and fix those in a sensible order.
Symptoms
- Sudden loss of power
- Stalling
- Fuel smell
- Fuel leak under the hood
Common causes
- Leaking high-pressure fuel line or fitting
- Cracked fuel rail
- Injector stuck open or leaking internally
- Failing high-pressure pump
- Faulty rail pressure sensor or relief valve
How to diagnose P0093
- Look for visible fuel leaks with the engine off first. Never feel for leaks on a running diesel: high-pressure fuel can cut into skin.
- Check the fuel filter for metal.
- Do an injector return test.
- Check the pressure relief valve.
How to fix it
- Repair the leaking line or fitting
- Replace the leaking injector
- Replace the pump or relief valve
Estimated repair cost
Likely repairs for P0093 run from about $400 to $6,000, depending on the cause.
| Repair | Typical range (parts + labor) |
|---|---|
| Diagnostic fee (scan + testing) | $100 - $200 |
| Diesel injector replacement (one) | $400 - $1,200 |
| Diesel high-pressure pump (CP3/CP4) | $2,500 - $6,000 |
These are rough US estimates for an independent shop in 2026, based on typical parts prices and standard labor times. Dealers, big trucks, luxury brands and high-cost areas often run higher. They are not quotes. Use the repair cost estimator to adjust for your vehicle.
How serious is P0093?
Severe severity
Stop driving. Diesel spraying on hot parts is a fire risk, and the engine may shut down.
Make-specific notes
Duramax (GM 6.6L)
P0093 shows up on several Duramax generations from leaking lines, injectors or pump problems, and on the LML from CP4 failures.
Always check open recalls and technical service bulletins for your VIN.
P0093 FAQ
What does P0093 mean?
P0093 stands for "Fuel System Leak Detected - Large Leak". The computer saw rail pressure drop much faster than fuel delivery explains, and decided fuel is leaking from the high-pressure system.
Can I drive with a P0093 code?
Stop driving. Diesel spraying on hot parts is a fire risk, and the engine may shut down.
How much does it cost to fix P0093?
It depends on the cause. The likely repairs for P0093 range from about $400 to $6,000 at an independent shop in the US, plus a diagnostic fee of roughly $100-$200. These are rough estimates; dealer prices and some vehicles run higher.
What is the most common cause of P0093?
The most common causes are: leaking high-pressure fuel line or fitting; cracked fuel rail; injector stuck open or leaking internally.