P018A — Fuel Pressure Sensor B Circuit

P018A points at fuel supply. The standard definition names the system involved; which part inside it has actually failed is what the checks below establish, cheapest first.

Common causes

The cause is almost always one of a few things. Here they are — P018A rarely comes from anything outside this list:

• Fuel filter blocked
• Pump worn and no longer making pressure
• Pressure regulator faulty
• Wiring or relay fault to the pump
• Blocked strainer in the tank

Where to start

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

1. Measure actual fuel pressure against specification — this code is about pressure, so guessing without a gauge wastes parts
2. Replace the fuel filter if it is due; it is the cheapest thing in the circuit
3. Check the pump relay and its supply voltage
4. Listen for the pump priming when the ignition is switched on
5. Replace the pump once the filter, wiring and regulator are ruled out

That is what holds for P018A 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.