What Does P018C Mean?
The fuel pressure sensor B circuit is outputting a voltage below the minimum expected threshold, indicating either very low fuel pressure or a sensor/wiring fault. The ECM cannot determine actual fuel rail pressure, which severely impacts fuel injection calculations. The driver may notice hard starting, stalling, power loss, or the engine may not start at all.
Common Causes
30%
Fuel pressure sensor B has failed with low or zero output voltage
25%
Short to ground in the signal wire of the fuel pressure sensor B circuit
20%
Actual low fuel pressure from a failing fuel pump
15%
Open or high-resistance ground circuit for the sensor
10%
Damaged sensor connector or backed-out pins
Diagnostic Steps
1
Check the fuel pressure sensor B PID — a reading of 0 psi or near-zero with the engine running points to either genuinely low fuel pressure or a shorted sensor circuit.
2
Install a mechanical fuel pressure gauge on the fuel rail to verify actual fuel pressure. Typical GDI systems run 500–2900 psi; port injection runs 40–65 psi. If mechanical pressure is normal, the sensor circuit is at fault.
3
Unplug the fuel pressure sensor B and measure the 5V reference (should be 4.9–5.1V) and ground (under 0.5 Ω to battery negative) at the connector.
4
With the sensor unplugged, check for continuity between the signal wire and ground — any continuity indicates a short to ground in the harness.
5
If actual fuel pressure is low, check fuel pump operation: listen for pump prime with key on, verify pump relay and fuse, measure pump current draw (typically 4–8A).
Estimated Repair Cost
$100 - $600
Parts + labor, varies by vehicle and location
The fuel pressure sensor B circuit is outputting a voltage below the minimum expected threshold, indicating either very low fuel pressure or a sensor/wiring fault. The ECM cannot determine actual fuel rail pressure, which severely impacts fuel injection calculations. The driver may notice hard start...
The most common cause of P018C (Fuel Pressure Sensor "B" Circuit Low) is: Fuel pressure sensor B has failed with low or zero output voltage
Typical repair costs for P018C range from $100 to $600, depending on the vehicle, location, and whether you do it yourself or go to a shop.
Exercise caution. If actual fuel pressure is low, the engine may stall without warning, which is dangerous in traffic. If only the sensor is faulty, the ECM may enter a reduced-power limp mode. Diagnose promptly.
Start by connecting an OBD2 scanner to read the code and any freeze frame data. Then follow the diagnostic steps specific to P018C to identify the root cause.
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Quick Info
Category
Powertrain
System
Fuel System
Difficulty
Type
Generic (SAE)
Recommended Tools
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