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P1093 — HP Fuel Rail Pressure Low During Power Enrichment
CriticalFuelStop as soon as it's safe
Seen on: Heavy Truck/Diesel
HP Fuel Rail Pressure Low During Power Enrichment. Common causes: CP3/CP4 pump worn.
Don't risk it — get a diesel tech on the truck.
Your code rides along, so nearby mechanics see the fault before they quote you.
How serious is it?
Critical. Stop as soon as it's safe.
Most likely causes
- CP3/CP4 pump worn
- Fuel filter restriction
- lift pump weak
First moves (roadside)
- Test lift pump volume and pressure
- replace HP pump if injection quantity test fails
FAQ
What does P1093 mean?
HP Fuel Rail Pressure Low During Power Enrichment. Common causes: CP3/CP4 pump worn.
How serious is P1093?
Critical — Stop as soon as it's safe.
What's the most likely cause of P1093?
The most common cause is: CP3/CP4 pump worn. Other possibilities include Fuel filter restriction; lift pump weak.
Can I keep driving with P1093?
Stop as soon as it's safe. When in doubt, get a qualified mobile diesel tech on the truck before continuing.
Throwing this code right now?
Find a mechanic or related guides
General diagnostic guidance for diesel engines (Cummins, Detroit, PACCAR, Volvo, Mack and more). Not a substitute for a scan-tool diagnosis on your specific truck.