Emergency Question about "Check Engine" light

I'm 50 miles from home on a short 100 mile weekend trip after the bus has been sitting for months. 95 chassis Series 60 XL 45 Royal Converstion.

On the road and the check engine light came on and bus began to throttle down. Pulled off on shoulder and immediateley checked belts, all fluid levels. Ok. Had issue with water level low sensor before so suspected that at first but it was fixed less than a few thousand miles ago. Could see the water line through the site glass. Threw a gallon of water in it on the outside chance it has sloshed enough to temp trip the light. Buying DDeck reader immediatley when I get home.

Took off and made it about 3-4 miles before it came on again.

Thought about jumping the low water sensor with paper clip as I had done prior when it was defective but called Prevost Service Hot Line and (didn't know this), I learned you can initiate a sequence of flashes by depressing the Overide switch and recording both Active Codes and Inactive codes. You veterans will know that Active Codes are something that is happening RIGHT NOW and Inacive codes are the history of everything that has happened. This is next best thing to a DDeck reader to point you in the right direction although not as detailed. Better than nuttin. Had list of codes and cross referenced to find the errors (won't bother with all the history codes, just the first few) Came up with code 14 which is "Coolant Temperature Circuit Failed High" or it could also be "Oil Temperature Circuit Failed High" (you need the reader on a few of these codes to know for sure but this narrows it down and points you in the right direction as I stated) and followed by code 44 which is "Oil Temperature High".

Technician felt that the first one (the history or Inactive Codes read back to you in the order of most recent as you would expect)........code 14 was either a sensor failing or a bad wire from sensor to DDECK. Possibly a temp voltage spike. Now, code 44 "Oil Temperature High". I don't know. My engine temperature at the gauge was and is fine at 190 or so. Could the oil pump be bad and the oil in fact overheating without causing the engnie to overheat ?

I'm in a shopping center where I'm probabley going to play it safe and stay put tonight until I get some replies. Remember I'm the guy that had my 94 Series 60 blow up without ANY warning (factory deffective wrist pins is the rumor) so I'm going to go with "caution" instead of "go for it" until I know. Got Good Sam's and AAA and rather use that instead of loose another engine.

Now I sat in the parking lot just now and ran the engine waiting to see if the Check Engine light would come on again and I could catch the "Active Code" and I did. It was code 44 or "Oil Temperature High. Over the course of 10 minutes I noticed it started doing it with some regularity. About every 2-3 minutes. I suspect that when I hit the Engine Overide button to reset it, it must take a few minutes to reset and pick up the error again and flash the Check Engine light.

So........I presume it comes down to figuring out if I really have hot oil or if if I have a bad sensor. My oil preasure gauge at the dash is reading 40 at idle. There's an aux gauge in the engine bay that I haven't compared yet.

I'm sitting here overnight. Is the oil pump inside the sump with the pan (and oil) all in the way or is it mounted enternally and how would I test it ? Remove the hose and turn the motor on momentarily ? Presume there must be an oil cooler that I haven't had the joy of poking around for yet. Maybe it's near there. 95 Chassis XL 45. I'll dig into the 5 CD's I have with technical stuff Monday morning I guess.

See the recent thread on the sensors. Harry Hoppe got the discussion going. Your problem is the sensor. It needs to be replaced.

Jeff: You are exactly where I was one month ago. Read Jons research on the part numbers and call a Detroit or Freightliner parts and order the sensors Jon lists. The High Temp Water and High Temp Oil are located on opposing sides at the rear of the engine up next to where the head joins the block. Because our engines are in backwards this is forward in the engine compartment as far as you can reach. Before removing the water sensor I suggest putting a clean bucket under the area to catch the coolant as it leaks out during the exchange of the sensors. The old one required an right angle air impact wrench to break it loose. We were along side the road 60+ miles from getting the proper matching anti freeze so we had to put water in to replace the lost coolant. This required a complete coolant change after reaching civilization.
It's a tuff job insstalling the sensor, you may want to get help. It will get you back on the road.

Harry-

Thank you for the added information. I've read Jon's detailed post and took his suggestion already and already ordered all the sensors as back up's. My water sensor was just replaced not that long ago and I'm not getting an error their anyway. I'm pretty sure it's the Oil Overheat sensor that I need. So I'll be switching that one out tommorow. Are there any ugly surprises awaiting me for that sensor besides needing to be quick on the draw so as not to loose to much engine oil ? I would presume given the engine temperature that teflon tape is not required but I have it on board. Should I just snug it up nice and tight ?

Regarding what you say about catching the coolant, I won't be changing that sensor although I ordered a back up. But I do think it's a good time to flush my coolant and replace it since I've never done it in 40,000 miles. I got the Prevost service manual but any tricks of the trade for that process welcome. Just drain and fill with new coolant / water mix or wonder if I should put some flush chemical in. If there's any build up or minor gunk, probabley better not to stir the S*&T and have it start rotating around the cooling system and wind up plugging up the thermostat later on. Yes ?

Also, regarding the sensor I'm relacing for the hot oil temperature. If that doesn't fix it, I presume that the next place to look is the oil pump or a clogged oil cooler ???? I've got oil preasure (40 at idle) so presume the pump is ok. Bracing myself for part B if the sensor change doesn't do the trick.

Do not use the white teflon tape around heat or oil, it will fail. They make special tape for that application, It has a yellowish color.

Jeff: The sensor will arrive with a coating on the threads that will provide the tight seal. As far as coolant, we are replacing the coolant with a long life coolant that has a CAT Spec. EC-1. Chevron or Cat brand with EC-1 spec comes pre mixed 50/50 Antifreeze and water. Or concentrated and you mix with 50% water. If you use this, no other additives are needed or wanted. Your water filter cartridge should not contain additives. Your system contains 24 Gal. It is hard to get all 24 gals out even draining webasto coolant from its piping system. We lifted the front of the bus to help it drain. There is a post on POG on 10/20/08 that covers the water.
There are two more sensors that can shut you down they read the timing on the flywheel to time the injectors. On a sreies 60 they are low, one on either side in the front of the engine. Part Nos. FRT 8929387 and FRT 8929388 I'm not sure if these are Freight Liner numbers or Detroit. They came from Freight Liner. Double check me on these sensors and numbers.

Thanks for replies. No yellow tape Joe so will tighten up as it comes.

Waiting for UPS and parts to arrive. Just started the bus cold and let idle for only 4 or 5 minutes to see if light would repeat right away as it did the other night when testing at operating temperature. Thought if it was a defective sensor it might come on cold. I'm certain you can't know for sure the answer to this but do you suppose it's possible that the sensor is throwing off a false reading but it only is doing so at operating temperature. In other words, the thermostat calibration (so to speak) is off and would not trigger with a cold engine, only when it's warm enough to trip it falsely.

I'll have to start analyzing again if I change that sensor and get 10 miles down the road and the light comes on again. Crossing my fingers the sensor change out will do the trick.

Jeff: You can have all the errors erased from your computer so the next time there is a problem, only the recent code will be displayed. The computer can be re-programed to eliminate the sensors shutting you down. CAUTION!! If you really do have a problem you will not know it until the damage is done. Fire trucks do have their sensors eliminated in the computer, so they cannot be shut down during a emergency operation. If their engine runs out of oil or other damaging condition, it will simply burn up. What the hey, the tax payers will just buy them a new one.

Harry- Thanks. Yes, I know Detroit can program it to do several differnet things including shutting down, misfiring to alert you or to do nothing. I have mine all set to misfire.

I had a new computer put in several months ago, so all the history WAS errassed but after the most recent errors, I continue to get low voltage this and that errors and that's proababley becuase the batteries went dead during sitting in between computer change and now.

3:30 and still waiting for parts. Might have to stay here another night yet.

Jeff,

What was the problem that shut you down?? What was the resolution?

My curosity got the best of me.

Hector