How to Diagnose Engine with Code P018C on Ram 1500 4th Gen GM Truck

If you engine is hard to start or won’t start at all, and engine lights is on with the code P018C, that relates to the fuel pressure sensor! This article will shows you how to diagnose engine with code P0018C on Ram 1500 4th Gen 2009-18, but this problem is also common on GM trucks, and could occur on any vehicle that monitors fuel pressure.

More cases about Ram truck, please refer to RAM 1500 PICKUP REPAIR.



There is a fourth generation Ram 1500 without drive ability issues, but have a check engine light with a code P018C. Which the description is fuel pressure sensor circuit low. What that code is referring to is the pressure sensor right here:


It’s on the drive’s side, on the top of the engine where the fuel line comes into the fuel rail.

The reason why you have this code is the PCM or the computer is trying to get a signal from that sensor and it’s getting a very low voltage signal. Which it’s inaccurate , so it thinks there’s either something wrong with the fuel pressure or the sensor itself.

We need to know the computer is actually seeing from that sensor. So we’re going to use the scan tool.

Click on “ Variable Speed Fuel Pump Actual Rail Pressure” and “Variable Speed Fuel Pump Desired Rail Pressure”, then confirm



Those are two readings. This results is without engine running.

If you don’t have the scan tool what you can do is look at the connector make sure the connector is on there and take a look at the wires, and see if the wires look good or not.

These the readings with the vehicle running.


The desired pressure should be 58 but above one is still stuck at 62.35.

So that’s pretty much saying that the sensor is not moving and it should have dropped down. 62.35 is a default, when we let the sensor is disconnected right now, if we plug the sensor in, it goes to zero.


If we wait a minute, it goes back to 62.35.


So we started out with this code the P018C, which is fuel pressure sensor circuit low. Now in the diagnostic flow chart what you need to do is disconnect he connector and turn the key on.

If you end up with code P018D,the circuit high which is pretty much the opposite. Then what the problem is actually the sensor itself, that basically tells you that the wiring to the sensor is working properly in the connector and that all you have to do is replace the sensor.

If you didn’t have scan tool like ours that you could view the data of the fuel pressure sensor, when you disconnected the sensor and you’ve got that code that’s another way you know that sensor is bad. If you disconnected that sensor and you didn’t get that other code, most likely you have a short somewhere the wire is contacting, something metal on the car.

So when you get that fuel pressure sensor code, you either have a bad fuel pressure sensor , bad wiring a connector or there might be a problem in the computer the PCM, more often than not it’s just a fuel pressure sensor.


And for more GM vehicles projects,check here:GM vehicle repair cases


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