check engine

[youngsamuel]

I have my check engine light coming on sporatically. It may be a coincidence but on my last trip as I would go down a hill then back up it would come on then go off. It's as if something is loose or a fluid is low. I checked the oil and the level is fine.
Any thoughts???

 

[youngsamuel]

I did a search in this forum and checked the wires and fluids all seem fine.

 

[davekc]

Hard to say for certain without seeing what the code actually is via a laptop. My first suspicion would be a coolant sensor at the reservoir. Could be a loose wire somewhere else, but that would be my starting point without any other information.

 

[greg334]

You got a cummins, there should be a switch on the dash that says something like eng dia. It is a momentary toggle usually on the far left.

With the truck shut off, hold the switch down, turn the key on and the check engine light should stay lite after the ecm cycles through the checks.

If it has a active code, then it will stop buzzing for a second, then spit out the code. It will be a three digit code with a second pause between each digit, don't release the switch until it stops for at least 5 seconds.

For example -

buzz buzz buzz buzz pause buzz buzz buzz pause buzz buzz buzz buzz

means 434 which is a common one, the ecm voltage is too low, check your cables.

Do you lose power when you are driving?

If so it could be a problem with the fuel pressure sensor.

Did you check your coolant level?

 

[chefdennis]

One thing to remember is that those "lights" even though they say "check engine", doesn't mean that it is always an engine issue...dropped of the 2005 PT Crusier that my youngest daughter will be driving when she turns 16 in a few months to have a few repairs made and have it just generally gone over. On thing i told the guy was the the "check Engine" light comes on from time to time, thinkin it was an emisssions issue...well he called, said he pulled the "codes" , it had a bad...POWER STEERING " sensor.....it was leaking and needed replaced....

 

[Deville]

What kind of motor do you have?

My Cat 3126 does the same thing, I have heard of other Cats doing the same thing. I believe it's an over speed sensor Mine will come on at about 2200 rpm & about 72 to 76 MPH on flat ground or a decline.

2400 rpm is engine cutoff, the light will only come on if my foot is on the gas, if i'm going up a hill the light will go off & I get that extra boost of power from the turbo & get up to 2400 rpm regardless of speed.

So IMO I think it's related to speed more than RPM, at 2400 RPM reagrdless of speed the fuel cutoff is going to engage.

 

[youngsamuel]

Sorry for the delay in reply I spent some quality time with my family last week. I am going to eat lunch then head out to the truck to test all of the input I received.

 

[youngsamuel]

You got a cummins, there should be a switch on the dash that says something like eng dia. It is a momentary toggle usually on the far left.

With the truck shut off, hold the switch down, turn the key on and the check engine light should stay lite after the ecm cycles through the checks.

If it has a active code, then it will stop buzzing for a second, then spit out the code. It will be a three digit code with a second pause between each digit, don't release the switch until it stops for at least 5 seconds.

For example -

buzz buzz buzz buzz pause buzz buzz buzz pause buzz buzz buzz buzz

means 434 which is a common one, the ecm voltage is too low, check your cables.

Do you lose power when you are driving?

If so it could be a problem with the fuel pressure sensor.

Did you check your coolant level?

The code is a 422.

 

[greg334]

422 Coolant Level Sensor Circuit

Check the coolant tank on the firewall. Make sure there is the right amount of coolant and to make sure the wiring is alright.

 

[youngsamuel]

I checked the wiring and as far as I can see it is fine. The coolant level is good but when I removed the cap there was a small amount of pressure released. I usually do my own PM's but had a shop do the last one. It looks like the coolant filter valve was not opened back up after the filter was replaced, which was approximately 3000 miles ago. I can't remember if vertical or horizontal is open. I suppose I will have to remove the filter to find out or at least loosen it. Could this pressure effect the sensor? The engine was cold when I removed the coolant cap.

 

[youngsamuel]

Okay vertical is open so the mechanic opened it back up. I still don't know why there was pressure if the engine was cold. Could it be my sensor is just bad?

 

[youngsamuel]

Thanks again for the info

 

[greg334]

Sorry, I missed those posts.

Well there could be another problem, the tank is full of crud or rust.

AND

Just thought about this - when did you replace the coolant tank cap, or what is called the radiator cap?

 

[davekc]

You can bybass the sensor and if all is well, replace the sensor. If you bypass the sensor and the light stays lit, problem is somewhere else.

 

[youngsamuel]

How do I bypass the sensor?

 

[greg334]

You can bybass the sensor and if all is well, replace the sensor. If you bypass the sensor and the light stays lit, problem is somewhere else.

True, didn't mention that because I don't know Samuel.

I had made that suggestion once about a little VW GTI and the guy didn't understand that once he was finished figuring out the problem to plug it back in - I bought his overheated GTI off of him.

 

[youngsamuel]

So how do I bypass the sensor? Just unplug it? Also I filled up on fuel yesterday and noticed the light came on very little then as the fuel level dropped the light came on more. Coincidence?

 

[greg334]

unplugging it won't work, the sensor need some fluid across the probes to work.

I was thinking about it but the only thing I thought of is to take it out and check it, make sure there isn't any rust clinging on it and check the tank.