Good Cummins mechanic in So Cal?

Colton Truck Terminal garage.

Good info, thanks.

Truck is throwing code P0191
Fuel Rail Pressure Sensor Circuit Range/Performance is the definition of the code. I'm calling BS on the dealer saying he needs new injectors.

Here's what I turned up:

What causes the P0191 code?
Faulty fuel pressure sensor
Faulty fuel pressure sensor circuit
Faulty fuel pressure sensor connector
Faulty fuel pressure regulator

(Doesn't mention anything about injectors)

Here is a comment for another forum.

P0191 Fuel Rail Sensor

"Can you get your hands on some silicone Dielectric Grease? a slight dab goes a long way. I was guessing on the plug, but it's a good start. I don't suppose you have a display, like a CTS. or a scanner available to see what the rail pressure is do you? "

Me Again wrote:
Here is a comment for another forum.

P0191 Fuel Rail Sensor

"Can you get your hands on some silicone Dielectric Grease? a slight dab goes a long way. I was guessing on the plug, but it's a good start. I don't suppose you have a display, like a CTS. or a scanner available to see what the rail pressure is do you? "

Don't have the truck here and don't know where the sensor is but guessing it's on the fuel rail. Don't have any way to check the fuel pressure with the tools I have here.

Please don't put dielectric grease on any of the injection sensors connections.
It WILL NOT make them conduct or work better and it absolutely will not cure a P0191 code.

2oldman wrote:
Colton Truck Terminal garage.

X2 one this one. Been there before. Professional all the way

If injectors are suspected then I would first try ultrasonic cleaning before replacing them. Hard to believe injectors could be worn out to the point of requiring replacement at 117k miles.

Regarding di-electric grease, it's possible for sensors to produce an out-of-range reading due to a poor electrical connection vs a truly faulty sensor. It costs nothing to pull the connector on the fuel pressure sensor, clean the connector and add a dab of di-electric grease. Start with the basics before throwing parts at it...

I would run away from that dealer as fast as possible....sounds like you goit a good recommendation for a shop.

Ron3rd wrote:
Dealer wants $4400 to put new injectors in. Not under warranty

Please, keep us updated on the outcome of this problem.

ScottG wrote:
Please don't put dielectric grease on any of the injection sensors connections.
It WILL NOT make them conduct or work better and it absolutely will not cure a P0191 code.

Some reading:

https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

Me Again wrote:

ScottG wrote:
Please don't put dielectric grease on any of the injection sensors connections.
It WILL NOT make them conduct or work better and it absolutely will not cure a P0191 code.

Some reading:

https://www.w8ji.com/dielectric_grease_vs_conductive_grease.htm

That doesn't really tell me much and it doesn't contradict what I know to be true from working as an Av. Tech. and FAA Airman.
Using dielectric grease on a connection, especially low level millivolt signals like some sensors use, will cause failures.
I made a lot of money by simply removing that gunk from connections that some hack tech. smeared it in and making avionics systems serviceable again.