Fix P018C: Mechanic’s solutions that WORKED

The P018C: Fuel Pressure Sensor “B” Circuit Low code signals an issue with the “B” circuit of the fuel pressure sensor, indicating that the circuit’s voltage is lower than expected. This sensor plays a crucial role in monitoring the fuel pressure within the engine. A malfunction in this circuit can lead to incorrect fuel pressure readings, affecting the engine’s performance.

P018C quick overview

Meaning	P018C: Fuel Pressure Sensor “B” Circuit Low
Is it serious?	This code can be serious as it may lead to poor engine performance, hesitation, and stalling.
Possible causes	– Faulty fuel pressure sensor – Damaged or corroded wiring and connectors – Problems with the fuel pump or its relay – Issues with the Powertrain Control Module (PCM) – Poor ground connections or power supply issues
How to diagnose?	Inspect Wiring: Check the wiring and connectors to the fuel pressure sensor for damage or corrosion. Test Sensor: Perform electrical tests on the fuel pressure sensor, including voltage and resistance checks. Monitor Fuel Pressure: Use a fuel pressure gauge to check if the actual fuel pressure matches the vehicle’s specifications. Check Grounds: Verify the integrity of ground connections related to the sensor and fuel system. Evaluate Fuel Pump: Assess the fuel pump’s condition and the functionality of its relay. Consider PCM: Investigate potential PCM issues, including updates or replacements. Re-pin Connectors: If corrosion or damage is found in connectors, consider re-pinning or replacing them.

How to fix P018C – learn from mechanics

I looked into P018C service cases at iatn.com website where in the private forums the mechanics seek advice from other mechanics. I looked up a bunch of cases to help you decide how to fix your issue and see what would a real mechanic do to solve it.

Case #1: RAM

Vehicle Information: 2017 Ram 1500 Rebel 5.7L

Issue + Repair History: Started with P018C for low fuel pressure circuit. Replaced fuel pressure sensor and connector, replaced fuel pump assembly, and replaced ECM, all with OEM parts. The vehicle then set a P018B code. Found 3.6V on the signal return wire at the sensor with it unplugged. Voltage went away when cutting the return wire at the ECM, leading to ECM replacement.

Suggestions to Fix Issue:

• Check if there’s voltage on the signal wire with the sensor disconnected.
• Consider rewiring the sensor to the 2022 diagram as Chrysler updated the wiring.
• Look into possible high resistance in the circuit or a high resistive short to ground.
• Check voltage at PCM and compare with the sensor’s voltage.

Final Fix: Rewired the connector to the 2022 specs as per the updated Chrysler diagram, which resolved the issue. The signal, return, and ground pin locations differed between 2017 and 2022 models.

Case #2: Chevrolet

Vehicle Information: 2010 Chevrolet Silverado 1500 LTZ 5.3L

Issue + Repair History:

• Initial problem: P018C (Fuel Pressure Sensor Circuit Low Voltage), P069E (Fuel Pump Module Requested MIL).
• Replaced fuel pump control module and programmed it.
• Discovered an Impco GM fuel pump simulator box indicating a CNG or propane conversion.
• Found open on the signal wire from fuel pressure sensor to FPCM.

Suggestions to Fix Issue:

• Check electrical connector pins at the fuel pump control module for burns or damage.
• Inspect fuel pump relay and fuse box for melting or damage.
• Monitor fuel pressure and signal circuit integrity.
• Consider the impact of the CNG/propane conversion on the vehicle’s fuel system.

Final Fix:

• Found the issue was related to the CNG conversion.
• Checked continuity from fuel pressure sensor to FPCM and addressed an open signal wire issue.
• Discussed with the customer the option of returning to the conversion company for further service.

Case #3: Ford

Vehicle Information: 2016 Ford Fusion SE 1.5L

Issue + Repair History:

• Hesitation mostly in the morning for 30 to 40 seconds, then runs fine.
• Replaced the Fuel Rail Pressure Sensor (Ford Sensor).
• Discovered an issue with the low-pressure switch.
• Code P018C (Fuel Pressure Sensor B Circuit Low) present.

Suggestions to Fix Issue:

• Consider carbon buildup on valves if it’s a direct injection system.
• Check for deposits or leaking fuel injectors.
• Wiggle harnesses and connectors while monitoring Fuel Pressure Sensor (FPS).
• Check for short codes and harness issues.
• Look into the low-pressure sensor’s involvement in the issue.
• Examine Fuel Low Pressure Sensor (FLP) location and functionality.

Final Fix:

• Replaced the low-pressure switch and resolved the issue.
• Located the switch by following the inlet fuel line from the high-pressure pump.
• The switch was found under the master cylinder on the lower left front.

Case #4: Ram

Vehicle Information: 2013 Ram 1500 SLT 5.7L

Issue + Repair History:

• Originally, the truck ran only for 10-15 seconds and stalled if put in gear.
• After replacing the fuel pressure sensor and power distribution center, and cleaning connector corrosion, it ran well.
• Codes P018C and P018D were present.

Other OBD2 Codes + Test Results:

• Fuel Pressure Test showed pressure at 58 psi, within the specification.
• All wiring to the fuel pressure sensor was tested and found to be good.

Suggestions to Fix Issue:

• Check if the vehicle had been exposed to extensive moisture or salt, leading to corrosion.
• Inspect all connectors for corrosion, especially the fuel pump module connectors.
• Monitor fuel pressure under load during a test drive.
• Look into possible software updates for the PCM.
• Consider checking the PCM connectors for water intrusion and corrosion.
• Replace the TIPM if necessary.

Final Fix:

• After thorough testing and replacing the PCM, the truck has been running without issues.

Case #5: Ford

Vehicle Information: 2013 Ford Fusion SE 1.6L

Issue + Repair History:

• The vehicle had poor idle quality, hesitation, misfire, and the MIL lamp was on.
• Initially, the water pump was replaced due to bad bearings.
• Both coolant solenoids were replaced, one as per TSB 13-5-5.
• ECU was reprogrammed by an outside company.
• After ECU reprogramming, a P1299 code appeared, causing engine management system shutdown and limp home mode.

Other OBD2 Codes + Test Results:

• B26B7 – Coolant solenoid C
• P018C – Fuel rail temp sensor
• P1299 – CHT over temp. limp mode

Suggestions to Fix Issue:

• Check the coolant temp sensor for coolant in the connector.
• Ensure cooling fans are working and check for fuse issues.
• Consider the possibility of incorrect ECU programming and address recall 17S09 for coolant level sensor installation.
• Check the coolant stand pipe for blockage.

Final Fix:

• The vehicle was taken to Ford for recall work, including the installation of a coolant level sensor. This resolved the issue.

Advice	Description of Diagnostic Step
Check Wiring and Connections	Inspect the wiring and connectors of the fuel pressure sensor for damage or corrosion.
Test the Fuel Pressure Sensor	Perform tests to verify the functionality of the fuel pressure sensor, including checking the voltage and resistance.
Inspect for Corrosion at Connectors	Check connectors, especially at the fuel pump control module and power distribution center, for signs of corrosion.
Monitor Fuel Pressure	Use a gauge to monitor the actual fuel pressure and compare it with the vehicle’s specifications.
Consider PCM/ECM Issues	Investigate potential issues with the Powertrain Control Module (PCM) or Engine Control Module (ECM), including software updates or replacements.
Check Grounds and Power Supply	Verify the integrity of ground connections and power supply to the fuel pressure sensor and related components.
Evaluate Fuel Pump and Relay	Assess the condition and functionality of the fuel pump and its relay for any faults or irregularities.
Re-pin or Replace Connectors	If corrosion or damage is found, consider re-pinning or replacing the affected connectors for a secure connection.