Mysterious Engine Light

woodtick · **Posted:** Wed Jun 25, 2014 12:30 pm

OK fellow CRDers, I have a recurring check engine light that shows occasionally up for no apparent reason. I have taken it to various auto parts places to use the code reader and nothing shows up. The light does go off on its own after +/- 5 key run cycles. There is little if any power loss and seems to be running fine. All fluids and maintainence are up to date.

I am stumped. Where do I start to look?

papaindigo · **Posted:** Wed Jun 25, 2014 12:45 pm

Best 2 answers I can give you, pick one although you may not like either:
1. ignore it. CELs come on when some computer system is "unhappy" about something. If it's a transient something the CEL will go away and as far as I know the code will clear on its own after 3-5 drive cycles. For example if you have an engine stall as a result of the transmission drain back issue that can pop a CEL that will go away as noted if the stall is not repeated: same for unplugged MAF sensor CEL-plug MAF back in code goes away. This of course assumes that it continues to go away; if it doesn't then go directly to #2.
2. while the CEL is on go to a DCJ dealer or some shop (not Autozone or some such but a real professional repair shop) that has a DCJ equivalent code reader that will read all codes not just the ECU. Have them pull the code which it should do if the CEL is on at the time the reader is plugged in.

DOC4444 · **Posted:** Wed Jun 25, 2014 8:21 pm

Starscan reads many codes that NOTHING else will on this vehicle. Also, it can access the memory, so the intermittent CEL will be able to be deciphered even if the CEL is NOT on when you bring it to a dealer.

DOC

woodtick · **Posted:** Thu Jun 26, 2014 5:19 pm

I was hoping to avoid another visit to the dealer or garage as work for me is uber busy right now. Nobody else has had a similar situation?

woodtick · **Posted:** Sat Jun 28, 2014 8:36 pm

DOC4444 · **Posted:** Sat Jun 28, 2014 11:16 pm

My post was because of being in a similar situation. I have tried all sorts of aftermarket scanners. The Innova 3030 seems to read more engine codes than most and is cheap. However, if the 3030 does not read the code triggering your CEL, time to go to the dealer.

DOC

woodtick · **Posted:** Sun Jun 29, 2014 8:27 am

Thanks Doc. That brings up another questiom. Does anyone know how in depth the Torque Pro app and Bluetooth adapter are compared to other scanners? I do not own a scanner so I'm thinking about getting one. Going to look into the reviews, etc. We Jeep people tend to do a lot of our own repair stuff so I am asking who has a scanner, what kind?, price?, and the pros/ con's. All info would be appreciated

DOC4444 · **Posted:** Sun Jun 29, 2014 11:05 am

Last time I used Torque Pro to try to read codes, it shut off the motor, but have not tried it with the latest iteration. With a $30 adapter, nothing is cheaper than Torque.

DOC

flash7210 · **Posted:** Sun Jun 29, 2014 12:24 pm

TorquePro works pretty good for me.

WolverineFW · **Posted:** Sun Jun 29, 2014 3:12 pm

I have never had an issue with Torque Pro reading codes ( at least ones it can access) and I have used it on a 2006 Jeep Liberty, a 2008 Sprinter and a 2003 Acura 1.7EL

woodtick · **Posted:** Mon Jun 30, 2014 7:29 am

Thanks for the input! Keep it coming CRDers !

minisub · **Posted:** Mon Jun 30, 2014 10:45 pm

I'm using an OBDLink scan tool and ScanXL on a laptop. Works fine so far, not much need for code reading so far, but logs and displays anything I can find a PID for without disconnecting or shutting me down.

Not wireless. Don't care. My phone is for making calls. Plus I have been doing much the same with EFI in the GMC for so long it seems "normal" to me.

woodtick · **Posted:** Wed Jul 02, 2014 6:45 am

Engine light not so mysterious anymore!

I went to another auto parts place to use the code scanner one more time and this one worked. I got codes P0107 and P0299. Time to start hunting down the issue.

I checked the driver side CAC hose and it was slightly oily in one spot. I could not find a hole or tear. I will have to pressure test it. I would think it should hold 25# of preassure , correct? How do I check the MAP sensor? I remember reading that a GM part is interchangeable. Does anybody have the part #?

Any other thoughts would be appreciated.

Thanks,
Doug

PS. Does anybody know why I'm not getting a notification for a post on subscribed topics?

GreenDieselEngineering · **Joined:** Sun Jun 07, 2009 5:10 pm **Posts:** 1111

P0107 is an open circuit in the MAP sensor. Check the wiring and if ok, buy a new sensor and problem will most likely we gone.

papaindigo · **Posted:** Wed Jul 02, 2014 9:13 am

Alternative and much cheaper MAP sensor is BOSCH # is 0 281 002 845 or GM PN 55206797

P0299 can be a melted vacuum line in heat resistant tubing near firewall below coolant tank but that sort of leak should come with a significant loss of power. Suggest you check air filter, airbox to turbo hose for crack in bottom of hose just in front of turbo, both CAC hoses (that oil spot suggest a porous hose) keeping in mind that the OEM spring clamps have a limited life cycle and really should not be reused, check the little $5 air filter that hangs off the side of the vacuum tower behind the airbox; turbo vane movement as that can be limited by sticky vanes or vacuum issues (You can check the vane functionality at idle in park. Underneath the vacuum actuator on the turbo is rod extending downward connected to the vane mechanism. If you pull off the vacuum line at the turbo, the arm should drop about 1/2 inch and then raise back up after reconnecting the vacuum line. It is a bit difficult to see the rod, but this is the easiest method to check for proper VGT vane movement.)

Check with dgeist on your subscription notice issue. I had a similar problem getting notice of messages that he was able to solve. Might be a similar issue

woodtick · **Posted:** Thu Jul 03, 2014 8:39 am

Thanks Kieth and Pap!
I will be checking those things soon.

Mysterious Engine Light

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