# P018C – Fuel Pressure Sensor “B” Circuit Low..



## Do0ks (May 29, 2021)

Hey, y'all.

Ugh, been chasing this issue for MONTHS now.
I've pretty much replaced the whole fuel system.
Fuel injectors, fpcm, fuel pressure sensor, fuel pump.

Tested voltage and continuity on wires, tested the fuses.

Car is running better then ever, but for some reason, it still thinks it has low fuel pressure. Runs at 55 psi at the injection rail.

I really need to pass inspection, when I take it to a mechanic they either don't know what's wrong with it or wants me to fix irrelevant issues.

Anyone have any ideas? I'm running out of possibilities that I can think of.


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## Thebigzeus (Dec 2, 2018)

How are you measuring it? Does the pressure at the rail match up with what the ECM reports?


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## Do0ks (May 29, 2021)

Thebigzeus said:


> How are you measuring it? Does the pressure at the rail match up with what the ECM reports?


Thanks for the reply. 

Actually, yes but I am confused because the ECU reads 0 psi, but it has a new fuel pressure sensor installed. (that was my first guess when I did the OBD2 diagnostics portion.) 

I did read somewhere that the Cruze doesn't have the ability to read fuel pressure through the ECU. I can get a few freeze frame reports if that helps at all. 

I keep going back to that thinking maybe it should show some kinda data.


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## Thebigzeus (Dec 2, 2018)

Hmmm have you traced the wire from the sensor to the ecu? Does it have voltage if you unplug the sensor and turn the ignition on?


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## Do0ks (May 29, 2021)

Thebigzeus said:


> Hmmm have you traced the wire from the sensor to the ecu? Does it have voltage if you unplug the sensor and turn the ignition on?


It does, if I remember correctly it was 5v in signal wire ( I could be wrong about the voltage, it's been awhile, but it definitely had voltage.)


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## Do0ks (May 29, 2021)

Here's some freeze frame data, if that helps anyone.

Idle:
=========================================================

Vehicle VIN:
Vehicle Manufacturer: Chevrolet
Vehicle Calibration ID: 126

Freeze frame information: 
------------------
Fuel Status = 0 byte
Engine Load = 32.549 %
Engine Coolant Temperature = 149 °F
Fuel Rail Pressure = 0 psi
Fuel Trim Bank 1 Short Term = -7.812 %
Fuel Trim Bank 1 Long Term = -10.938 %
Intake Manifold Pressure = 7.397 psi
Engine RPM = 789.75 rpm
Speed (OBD) = 0 mph
Timing Advance = 6 °
Intake Air Temperature = 84.2 °F
Mass Air Flow Rate = 3.66 g/s
Throttle Position(Manifold) = 24.706 %
Run time since engine start = 123 s
Fuel Level (From Engine ECU) = 28.627 %
Distance travelled since codes cleared = 46 miles
Evap System Vapour Pressure = -3.75 Pa
Barometric pressure (from vehicle) = 14.069 psi
Catalyst Temperature (Bank 1,Sensor 1) = 809.6 °F
Voltage (Control Module) = 14.517 V
Engine Load(Absolute) = 34.902 %
Commanded Equivalence Ratio(lambda) = 1 
Relative Throttle Position = 11.373 %
Ambient air temp = 82.4 °F
Absolute Throttle Position B = 24.314 %
Accelerator PedalPosition D = 20 %
Accelerator PedalPosition E = 9.804 %


End of report.
*__*


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## Thebigzeus (Dec 2, 2018)

Was this always the issue? I am wondering if the replacement sensor isn’t bad. Is it OEM?


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## Do0ks (May 29, 2021)

Thebigzeus said:


> Was this always the issue? I am wondering if the replacement sensor isn’t bad. Is it OEM?


Yeah, it's been a issue shortly after I got the car. Originally, testing and noticing no pressure I instantly thought the fuel pressure sensor but after changing it out the same code existed and no change in the car occured. 

I've also saw people with the same code had to change out the negative battery terminal and or replace the camshaft positioning sensors. It seems unbelievable to me, but then again, it seems like the whole system is linked in these newer cars..

I'm waiting for a day I get a flat tire and somehow that effects my mass air sensor or some crap like that.


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## Thebigzeus (Dec 2, 2018)

Very true it could be related to this: Special Coverage #14311: Negative Battery Cable

Edit: oh wait, this is in the Gen 2 forum, do you have a newer Cruze?


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## Do0ks (May 29, 2021)

Thebigzeus said:


> Very true it could be related to this: Special Coverage #14311: Negative Battery Cable
> 
> Edit: oh wait, this is in the Gen 2 forum, do you have a newer Cruze?


Yeah, I have a gen2. 
Worth a try I guess, before I'm done I just might have a new gen2 with how many parts I'm throwing at it. Lol


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## Do0ks (May 29, 2021)

It's a no go. Also just replaced the fuel pipe. 

Killing me!!


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## Do0ks (May 29, 2021)

Okay! Figured it out!!! 

It was a break in the wiring located in the passenger rear wheel well just past the harness behind the splash shield. 

Ran a continuity test and found the single wire was barely connected when I moved the wires. Makes sense as to why I got some voltage when testing on the fuel pressure sensor, must of moved the wires perfectly. I just cut the wire at the break and bypassed the harness with a jumper and it's good as new.

I ended up getting my hands on the gm repair manual, don't ask how I did but it does say the code p018c is definitely a break in the single or ground wire. 

So, anyone has this code the first thing to do is run a continuity test between the wiring harness and the fuel pressure sensor connector on both the signal wire and the ground wire. 

What a **** show.


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