This morning when I started my truck (62 degrees) the "Check engine soon" light came on. I turned it off and checked the oil, water level and trans fluid.. There wasn't anything strange looking under the hood. I started it up and the light came back on. I live in the country and was going to town, 7 miles, and when I got to town the light went off and has not come back on. The closest diesel repair is in Corpus approx. 65 miles away.
What would cause this light to come on ?
And if it comes on again and I drive to Corpus and it goes off, can they diagnose the problem or does the light need to be on ?
Thanks,
Robert

 

When the light goes on, it stores a code. Injector Control Pressure sensor is a common cause for this right about now... but that's speculation on my part. If the truck runs quieter and weaker than normal, that ICP sensor jumps to the front of the suspect lineup. If cylinders start missing, the Under Valve Cover Harness rolls into view.

If you an Android tablet or a PC laptop and enough money to spend on having a shop hook up, there are options where you can do it yourself as often as you like for the one price. Search for Torque Pro or AutoEnginuity on the forum.

 

Thanks, but I'm retired and on a fixed income..
I'll check the ICP..

 

Tugly's point was you can probably get the equipment to scan it yourself for less than the cost of what a Ford dealer would charge you to scan it once plus the fuel to drive there. I have an Android phone, so I paid $4.95 for the Torque Pro app, and another $11.95 for a bluetooth OBD-II adapter.

 

That's the price of 4 gallons of diesel.

 

I took my truck to a guy with a scanner.
He says he checked everything there was to check and didn't find any codes.
He's been in the business for well over 30 years so he ought to know what he's
doing.
The SES light came on again and it feels to me like it's running ruff and sluggish.
Again, the light went off and it runs normal..
I'm at a loss..
Any suggestions ?

 

If the light came on, there is a code stored. If you want to guess, we can try that too. I have four guesses right off the bat, that COULD cause similar symptoms. My first is under valve cover harness is loose, my second is the ICP sensor is starting to go bad, my third is you have a chaffed wire on the harness somewhere. Fourth is the CPS is going bad.

 

Nothing against your guy who's been in business for 30 years, but unless he's got experience working on the powerstroke engine, he likely didn't use the right scanner. The 7.3 engine was designed to be a medium duty truck engine, and therefore does not use OBDII to relay engine codes. Per Federal law, the truck does provide OBDII generic codes for things like brakes, etc., but not engine specific codes.

Perhaps another S Texas member that has a scanner will read this and offer to read the codes for you.

 

Yep, like everyone else has said - if the check engine light comes on there is a code. Need the correct scanner or else you'll be chasing your tail....

 

I'm out working on my truck today, lmao, chasing my tail ...
I'm probably going to replace the CPS ...
Also check the ICP ..
If there is a code stored how do you clear it ?
Is there a reasonability priced scanner I can get to scan this myself and what brand, type, etc. will work ? Anything on e bay worth a flip ?
I'm also calling Coastal Diesel in Corpus to see how much they charge to scan, that's about all they work on are Fords especially 7.3 ..

 

RobertJohn...

Your own words best described what you appear to be doing. Before needlessly spending any of your finite fixed income on shot in the dark parts replacement, please go back and read Tugly's first response to your thread.

If you have an Android phone, then you can read the codes for about $16.00. Not just one time, but everytime, for as long as it takes to clear codes, make changes, and see if the code sets again.

If the SES light came on, then a code set. If whoever your trusted person is could not find the code, then find a new person, or find a way to read them yourself (ie, the $16.00 solution).

Adding to Jason's guessing game, the other day out of the blue my Service Engine Soon light came on just like yours. It was not the CPS, the UVCH, the IPR, the IPC, or any other usual suspect. Truck ran fine, but there was the light again. I scanned the truck, and found P0237... the MAP sensor signal return was low... (lower than 0.04v). Who'd have thunk it? I cleared the code, fiddled and diddled with the MAP sensor wiring, and then the code went from intermittent to persistent. If I had to return to a friend or a Ford dealer each time to clear the code, fiddle and diddle, then test for the code, I'd wear out a lot of favors, or a lot of diagnostic fees, quite quickly.

Around here, Ford charges $160.00 for a diagnostics check with their scanner. Compar that to $16.00. And knowing dealership service departments, they would have hit me for a new MAP sensor (major bucks), which I did not need. My MAP sensor was fine, and I had the tools on hand to verify that. I could also see what the reference voltage was, and what the condition of the signal was between the MAP sensor and the PCM.

The point being made by everyone who has responded is that anything short of determining the specific DTC that set your check engine light amounts to chasing your tail, and that is likely to cost you more in the long run.

 

Y2KW57,
I do appreciate your reply as well as Tugly and every ones.
I do not have an android phone, all I've got is a cordless land line.
And I don't think that will work..
I replaced the CPS and checked the ICP and there was no oil at all in it.
I called Coastal Diesel in Corpus and was told I'd have to leave the truck
for a min. of 2 days, how am I suppose to get home ?
That's why I was asking about code readers etc..
Also I was wondering what to do or where to put the ground end of my
ohm meter if the red in goes in the hole for the cylinder ?? Also, what
readings should I expect ?
Thanks again

 

I understand completely about not having a smartphone. I'm about to get rid of mine. As soon as I fully retire, that thing is GONE.

Now, as to your situation... you got a light, but your truck ran fine, right?

And then, the light went out on it's own, and hasn't come back, right?

Still, you've changed your CPS, and now you are stabbing the 42 pin connector with your DVOM to ohm out injectors, right?

If the truck runs fine, and the SES light did not come back, I'd close the hood.

Leave well enough alone, because you did NOT report a hard start, rough run, low power, miss, strange noise or leak issue. You saw a light. There are many good ways to diagnose motor issues without a scantool (compression test, dye leak test, blow by test, experience, etc). But you got a light, not a mechanical smoking gun.

In your case, the most efficient way to learn what the light meant is to look at what DTC was recorded in the PCM, because that was all you had. No obvious symptoms, just a light. And in your case, the light isn't even there anymore. It could have been just a fluke. If after a certain number of drive cycles have passed without the light returning, you could be out o the woods.

In my recent case, even while I knew exactly why my light went on, I have no clue what I did to "fix" it. I'm not sure that I did anything with my fiddling and diddling. But my light hasn't returned either. Yet. Again, the actual cause was nothing like what is typically discussed on the forums. And like you, I had no discernible driveabllity symptoms.

 

The light has come back on and it runs kind of ruff. Once the light goes out it runs fine. I've just finished watching a video on the 50cent fix and how to tell which side it is needed on etc.. That will be my next move. Tomorrow I'm taking it to another mechanic friend who has a scanner and says he can read the codes etc.. Depending on what he finds will determine my next move.

 

Just before he goes to read the codes disconnect the ICP sensor(P121* code) or the air intake heater (P0541 Manf Intake Air Heater Circuit Low ) or the EBPV(P0475 Exhaust Pressure Control Valve Error ). With any of those disconnected he should see a code I listed for it. If he doesn't the scanner can't read the codes on a 7.3L