P0253 — Fuel injection pump signal is too low

The engine’s fuel injection pump is sending a weaker than expected signal to the control system. This usually means the pump’s fuel metering control circuit is malfunctioning, causing poor fuel delivery. It can lead to rough running, reduced power, or stalling.

Common causes

The cause is almost always one of a few things. Here they are — P0253 rarely comes from anything outside this list:

• Faulty injection pump control sensor or wiring
• Loose or corroded electrical connectors
• Damaged fuel injection pump
• Faulty engine control module (rare)
• Low fuel pressure or clogged fuel filter

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Check and clean electrical connectors at injection pump
2. Inspect wiring harness for damage or corrosion
3. Test fuel pressure and replace fuel filter if needed
4. Replace faulty injection pump control sensor
5. Replace injection pump if internal failure confirmed

That is what holds for P0253 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.