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Red engine light shut down
Oil pressure guage on dash 0 engine shut down. On side of road e of Durango CO. Oil full. On phone with Prevost pass.
Engine code 128
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17 Replies
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On way back from Farmington NM with new oil pressure sender and a oil pressure test gauge.
2000 Featherlite H3-45
2024 Jeep Grand Cherokee
Leesburg, FL -
Problem fixed, details later!
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CONGRATS on fixing it!
Know that was an unsettling experience!
Please do let us know the details when you have time.
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THE EVENT
We left Durango, CO on Thursday 30 June looking forward to a short scenic drive to Santa Fe, NM. About 6 miles east on route 160 the red engine warning light and beeper came on. Quite disconcerting – the road had inches wide shoulders and no turn offs in sight. Hit the override button 2 or 3 times while looking for spot to pull off the road. Finally saw a spot where route 223 came in on the left. Pulled over to the left, totally blocking the two lanes of the incoming side road – red box on map. Engine shut itself down. Made a panicked unhooking of the toad, then got back in the bus to restart and maneuver it around into the wide gravel spot shown in the photo below, NE of the intersection – green box on map. Well, at least safely off the road.
Fortunately, during the entire several minute scramble only one vehicle came from the north and none apparently tried to turn north from 160.
Thanks to the redundant systems in our coaches, we were able to fire up the generator and enjoy a comfortable environment while pursuing repair.
THE BACKSTORY
About a month ago The DDC panel displayed a “CHECK ENGINE AT NEXT STOP” message. I ran through the codes on the display. It showed past codes of coolant level low, and engine oil pressure high, and a current active code of engine oil pressure high. As the engine had relatively fresh oil and filters, I figured it was a sensor gone out of range. Also the dash oil pressure gauge showed a little over 60, which in hindsight was a change from the prior “normal” where it typically showed a little under 60. I binned it in “one of these days I’ll look into it further” category.
SEARCH FOR HELP
Sitting in the gravel turnout, we pondered what next? I posted the note on PC. We called Prevost PASS who proved to be very helpful with technical support and doing some leg work for us, identifying the nearest Detroit service facility and parts source, and found the later to be determined critical part – the engine oil pressure sensor. During discussion with the Prevost tech he said his past experience showed a common failure mode for this sensor is to read high. He cited turning on the key and not starting the coach and the sensor would read a low end of scale pressure instead of 0. I don’t recall ever seeing or noting if that happened on mine, but I was not looking for it. As I mentioned, it did start reading to the right of 60 instead of left of 60 when engine was running.
PASS called back said dealer Lonestar Truck in Farmington NM was closest service facility but did NOT offer road service. Said they did have the oil pressure sensor in stock. Also said no other service providers anywhere near us.
Prevost PASS was very thorough in their follow up, they called me back 3 times until we verified problem was fixed.
GO GET PART
We jumped in the Jeep to head for Lonestar Truck in Farmington, NM to get part number DDC23532797. Picked it up for a little over $90. Also stopped at O’Reillys to get a 1 ¼” deep socket, and a “mechanical” oil pressure gauge kit.
THE REPAIR
I used the 1 ¼” deep socket and and extension with a ball swivel on the end to remove the old sensor. It is at the curbside upper forward end of the engine above the starter. I removed the stainless “box” that Liberty put above the batteries for storage of ??? years ago, so my task was a little simpler that day. Sensor is pretty tightly packaged with a wraparound morass of wiring harness forward and below, actually abutting the sensor, more about that later. Came out easy enough but had moderate difficulty getting the new sensor installed due to interference from the wiring harnesses in the area. I always try to finger start threaded connections to ensure no cross threading but struggled for some time trying to do this while hanging out of the engine bay leaning on the battery plastic shield with my legs dangling in the air reminiscent of Dan Hilger’s Monkey Boy story. I ultimately put the sensor back into the socket/swivel/extension and used it’s additional leverage to butt the pipe thread end to the hole and use the assembly to push the wiring harness aside enough to have a straight shot into the pipe threaded hole in the block. I made at least a full turn turning the extensions by hand without a ratchet to ensure no cross threading. Snugged it up, and reinstalled the wiring plug which was also a struggle as the green silicone seal is a tight fit between the male end of the plug and the hole in the sensor, some light oil will help with this.
I had debated whether to use the oil pressure gauge kit before installing the sensor to see if there was actually an oil pressure failure, which if it was the case, tow time. If good pressure but still engine shut down warnings, keep pushing the button and drive it to the Detroit service shop in Farmington for further diagnosis with tester the next day. I decided to just put the sensor in and see what happens. If still no good reading, then take it back out and test the pressure. Turns out when it fired up the oil gauge on the dash popped back up to its “normal” position just left of 60, and no engine lights. Whoohoooo!.
Make sure you have a deep socket and that the actual fastener engaging portion of the socket is deep enough to accept the sensor with room for the plastic part. Many deep sockets only have the hex part for part of their depth and a shoulder beyond that. The one I got let it go over about 2/3 of the brass nut part of the sensor so was good enough for the job.
LESSON(S) LEARNED
A corollary to the proposition “If it ain’t broke don’t fix it” is “If it is a little broke, be sure you know what will happen if it breaks, and what it will take to fix it”. In hindsight, I should have checked this out at home, verifying engine oil pressure mechanically, and at the least bought and carried a new sensor with us. I recall past posts on things that will “shut you down” and oil pressure is one of them. Should have verified had the needed tools and ability to do a field repair. Maybe call and talk to Prevost tech about what might come next with the indicated problem. Hindsight is great isn’t it?
Don’t run too low on fuel or fresh water, you never know when you might be living in the coach on side of the road for a while.
I will probably mount an analog mechanical oil pressure gauge somewhere visible on the engine.
INCIDENTAL FINDING
You can see in the close up photos of the failed sensor a significant curved “notch” worn in the plastic and even brass. This was from the wiring harness and dirt/oil slurry abrasive action from engine vibration over 22 years. I’m not sure how thick the plastic wall of the sensor is in that area, but it looks concerning enough that were it where I could see it, I would have replaced the sensor and shifted or shielded the harness from doing this further. If it had not failed internally, perhaps this would have worn through and caused an oil leak at some point.
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Incredible write-up, excellent detail – cause/effect, Solution and How To!
Definitely will have my mechanical friend help check this out before beginning our nearly 2-month trek North, Central and ultimately back to Southern Cal.
Thank you for the Heads-up!
Safe travels.
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David:
Thanks for taking the time to follow up. Great input, will be visually checking mine and watching the gauge closer the next time we drive.
Chuck
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Well done David. I always carried the 3 sensors that normally shut you down, oil pressure, high coolant temp and low coolant. Never had to use them over the years, guess it was good ju ju.
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Awesome write up David. Thanks! Like Tom, I’m getting the sensors.
I will probably change them now, and carry the old working parts for spares, and the necessary tools.
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Great explanation David. Your posts are always very helpful.
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Dave,
Glad you got it sorted. BTW…..I grew up in McAlester, OK. Been to Talihina many times……
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I hesitated to post this earlier and still feel uncomfortable with what follows.
If you are comfortable that the problem according to the code is in fact not real I believe the sensor you replaced can be bypassed from the system and the wire leads jumped to get you to service. A Detroit service facility or the Detroit 800 number can confirm that.
But you have to be confident it is a sensor problem and not a real problem, obviously because the real problem will destroy the engine as you drive for service.
Steve Magown
2001 Featherlite H3
West Monroe, LA -
I did indeed think of bypassing the oil sensor with a jumper. I did not make that my first shot at getting back going because as Jon said if there really was 0 oil pressure the engine would be toast.
I do have an OTC engine/transmission oil pressure test set, but it was at home on a shelf, doing me no good on the fateful day.
I bought a pressure test guage at OReillys while I was in Farmington. This is not really a test tool, but designed to be installed in a vehicle to give a mechanical analog reading of oil pressure. Comes with a 2″ gauge, some very small and fragile looking hard plastic tubing, matching compression fitting on back of gauge and a provided matching 1/8″ male compression fitting as well as a 1/8″ to 1/4″ brass bushing. Just what I needed to test oil pressure, the oil sender hole in block is female 1/4″ pipe. I detailed what I planned to do with this in my last post, but ended up not needing to use it. I mentioned earlier, I am likely going to install a mechanical oil pressure gauge somewhere visible on the engine. I may use the gauge from this kit, but will likely install it with a manual shut off small ball or needle valve between the engine oil pressure source and the gauge. I just don’t fully trust a $26 dollar gauge from China enough to add it as another potential oil leak point carrying full engine oil pressure going down the road.
Had I not been able to get a new sensor, but could get the oil pressure verified with the above gauge, I probably still would not have jumpered the wires unless I could have gotten verification of which pins to jumper. The wiring diagram in the link below shows a ground, an EOP (engine oil pressure likely) signal, and 5V+ as the three wires connecting to the sensor. My fear was as the other end of these wires likely connected to the ECU, if I sent aberrant voltage (the full 5+) or grounded the signal lead to the ECU there was some risk of frying the ECU.
My guess is the Sensor functions by an internal transducer varying the signal voltage from some low to high value based on the oil pressure it sees. Maybe some day when I get a spare moment I’ll put together a set up shown in the 5th box in the link below with my yet to be purchased spare oil pressure sensor and see what happens with signal voltage as pressure varies. I’m not holding my breath until that day.
As Lonestar said he was going to do, I am going to buy spares of all three “shutdown causing” sensors and install the other two, next time I get to working on the bus at home.
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I did indeed think of bypassing the oil sensor with a jumper. I did not make that my first shot at getting back going because as Jon said if there really was 0 oil pressure the engine would be toast.
I do have an OTC engine/transmission oil pressure test set, but it was at home on a shelf, doing me no good on the fateful day.
I bought a pressure test guage at OReillys while I was in Farmington. This is not really a test tool, but designed to be installed in a vehicle to give a mechanical analog reading of oil pressure. Comes with a 2″ gauge, some very small and fragile looking hard plastic tubing, matching compression fitting on back of gauge and a provided matching 1/8″ male compression fitting as well as a 1/8″ to 1/4″ brass bushing. Just what I needed to test oil pressure, the oil sender hole in block is female 1/4″ pipe. I detailed what I planned to do with this in my last post, but ended up not needing to use it. I mentioned earlier, I am likely going to install a mechanical oil pressure gauge somewhere visible on the engine. I may use the gauge from this kit, but will likely install it with a manual shut off small ball or needle valve between the engine oil pressure source and the gauge. I just don’t fully trust a $26 dollar gauge from China enough to add it as another potential oil leak point carrying full engine oil pressure going down the road.
Had I not been able to get a new sensor, but could get the oil pressure verified with the above gauge, I probably still would not have jumpered the wires unless I could have gotten verification of which pins to jumper. The wiring diagram in the link below shows a ground, an EOP (engine oil pressure likely) signal, and 5V+ as the three wires connecting to the sensor. My fear was as the other end of these wires likely connected to the ECU, if I sent aberrant voltage (the full 5+) or grounded the signal lead to the ECU there was some risk of frying the ECU.
My guess is the Sensor functions by an internal transducer varying the signal voltage from some low to high value based on the oil pressure it sees. Maybe some day when I get a spare moment I’ll put together a set up shown in the 5th box in the link below with my yet to be purchased spare oil pressure sensor and see what happens with signal voltage as pressure varies. I’m not holding my breath until that day.
As Lonestar said he was going to do, I am going to buy spares of all three “shutdown causing” sensors and install the other two, next time I get to working on the bus at home.
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Well I don’t know what I was doing wrong but the text lines kept going long off the right of the screen. Finally deleted the last link and it seems to format OK in the next post. The link is all there on the prior note even if you can’t see it all, just copy beginning to end and it should work. Also the picture shows the key points anyway.
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I did indeed think of bypassing the oil sensor with a jumper. I did not make that my first shot at getting back going because as Jon said if there really was 0 oil pressure the engine would be toast.
I do have an OTC engine/transmission oil pressure test set, but it was at home on a shelf, doing me no good on the fateful day.
I bought a pressure test guage at OReillys while I was in Farmington. This is not really a test tool, but designed to be installed in a vehicle to give a mechanical analog reading of oil pressure. Comes with a 2″ gauge, some very small and fragile looking hard plastic tubing, matching compression fitting on back of gauge and a provided matching 1/8″ male compression fitting as well as a 1/8″ to 1/4″ brass bushing. Just what I needed to test oil pressure, the oil sender hole in block is female 1/4″ pipe. I detailed what I planned to do with this in my last post, but ended up not needing to use it. I mentioned earlier, I am likely going to install a mechanical oil pressure gauge somewhere visible on the engine. I may use the gauge from this kit, but will likely install it with a manual shut off small ball or needle valve between the engine oil pressure source and the gauge. I just don’t fully trust a $26 dollar gauge from China enough to add it as another potential oil leak point carrying full engine oil pressure going down the road.
Had I not been able to get a new sensor, but could get the oil pressure verified with the above gauge, I probably still would not have jumpered the wires unless I could have gotten verification of which pins to jumper. The wiring diagram in the link below shows a ground, an EOP (engine oil pressure likely) signal, and 5V+ as the three wires connecting to the sensor. My fear was as the other end of these wires likely connected to the ECU, if I sent aberrant voltage (the full 5+) or grounded the signal lead to the ECU there was some risk of frying the ECU.
My guess is the Sensor functions by an internal transducer varying the signal voltage from some low to high value based on the oil pressure it sees. Maybe some day when I get a spare moment I’ll put together a set up shown in the 5th box in the link below with my yet to be purchased spare oil pressure sensor and see what happens with signal voltage as pressure varies. I’m not holding my breath until that day.
As Lonestar said he was going to do, I am going to buy spares of all three “shutdown causing” sensors and install the other two, next time I get to working on the bus at home.
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