Author Topic: Oil Pressure Sensor - CEL on intermittently - Degraded Engine  (Read 621 times)

Paul Haaf

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Oil Pressure Sensor - CEL on intermittently - Degraded Engine
« on: September 28, 2021, 09:28:35 PM »
On a short trip last weekend our red Check Engine Light turned on followed by a blue Engine Warning light. I noticed the Dash Temp reading was not even in the scale, it was pointing directly left.

The cycle repeated about 5 times in a 20 minute span. The engine also reduced power and slowed to about 45 mph. This cleared up as soon as the lights went out.

Aladdin showed Engine temp at 204 and transmission at 212 during this episode.

I checked coolant and the reservoir was fine but there was a little fluid on the bottom tube of the reservoir and on the lower coolant hose. I tightened the hose clamps and looked for anything else disconnected. Wires near the cooling sensor are exposed as the black wire loom has deteriorated and one wire appears cut, probably from previous service, i didn't find another loose wire it could have connected to. I plan to replace the wire loom and double check the conductors for damage.

I looked in wire schematics but none show how the dash gauge connects to sensors or the ECM. The light works on it and there are three other wires connections all sound.

About a month ago I rebuilt the seals on the Hydro pump solenoid, my first trip it ran hot and cut back at 225 degrees, I adjusted the solenoid and the next road test was fine and have put over 1000 miles on since with no issues.

If you made it thru all of this, nice job!

Update #1

The local Freightliner service center replaced the oil pressure sensor.  Then tried to test drive the coach; oil pressure read a steady 57 PSI and never changed.  When the coach was put in drive, it immediately lost power and could not be driven.  They had to return to the service facility in reverse!  That was the only way they could get it to run with power.  After talking to a CAT service advisor they decided to flash the ECM.  This enabled the new sensor to give proper readings that fluctuated with engine RPM.  However the power issue remained; they are stumped at what to do next.  The only thing they noticed was turbo readings are at 0 so they're thinking it could be a faulty sensor there.  They're planning to swap out that sensor tomorrow.  It never showed any other check engine lights but just won't run.  They suspect that something could be happening on the 5 volt sensor bus affecting operations.

Update #2
They replaced the Turbo Pressure sensor today and called to saw it is now fully resolved. I hope to be able to pick it up tomorrow and road test this week!

 
« Last Edit: October 25, 2021, 10:03:13 PM by Paul Haaf »
2006 Monterey-Ventura-IV 36'
CAT C9 400HP - Allison 3000

Looking to add a tow vehicle
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Paul Haaf

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Re: Dash Temp Gauge Not working - CEL on intermittently
« Reply #1 on: October 20, 2021, 02:59:17 PM »
Update on this issue:
I brought it to a local Freightliner service center and they diagnosed a faulty Engine Oil Pressure sensor, that was putting on the CEL and affecting the engine running properly.

I have it in the service center again now to have the oil pressure switch replaced and so far all analog gauges are working properly. The Aladdin gauge always drops to 0 PSI when the CEL turns on but the analog gauge is always around 1/3. It usually lasts a minute or two and then clears. The engine degrades and then restores. It has been a nuisance but has not stranded us.

I will update again after the repair is done.
 
2006 Monterey-Ventura-IV 36'
CAT C9 400HP - Allison 3000

Looking to add a tow vehicle

Steve Huber Co-Admin

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Re: Dash Temp Gauge Not working - CEL on intermittently
« Reply #2 on: October 20, 2021, 03:28:10 PM »
Paul,
A faulty/intermittent oil pressure sensor could cause your symptoms. The readings on the Aladdin are normally the ones the ECU sees while the dash gauges are pretty much "for entertainment only". Your reported engine and tranny temps are normal for the C9.
Steve
Steve
2015-          07 Contessa Bayshore C9,  400 hp
2013-2015: 00 Marquis Tourmaline, C12, 425 hp
2005-2013: 01 Contessa Naples, 3126B, 330 hp

Paul Haaf

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Re: Dash Temp Gauge Not working - CEL on intermittently
« Reply #3 on: October 25, 2021, 02:21:51 AM »
I have an update to this issue and request for more info!

The local Freightliner service center replaced the oil pressure sensor.  Then tried to test drive the coach; oil pressure read a steady 57 PSI and never changed.  When the coach was put in drive, it immediately lost power and could not be driven.  They had to return to the service facility in reverse!  That was the only way they could get it to run with power.  After talking to a CAT service advisor they decided to flash the ECM.  This enabled the new sensor to give proper readings that fluctuated with engine RPM.  However the power issue remained; they are stumped at what to do next.  The only thing they noticed was turbo readings are at 0 so they're thinking it could be a faulty sensor there.  They're planning to swap out that sensor tomorrow.  It never showed any other check engine lights but just won't run.  They suspect that something could be happening on the 5 volt sensor bus affecting operations.  Can anyone think of any other reasons for this behavior?
2006 Monterey-Ventura-IV 36'
CAT C9 400HP - Allison 3000

Looking to add a tow vehicle

Dave Atherton

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Re: Oil Pressure Sensor - CEL on intermittently - Degraded Engine
« Reply #4 on: October 30, 2021, 06:27:14 AM »
Paul, this sounds like IAP sensor ( cat part number 224-4526 ) has failed. How you can reinforce
that thought by disconnect the triangle connector that connected to the IAP sensor 15 inch pig tail.
Location of the IAP sensor directly in back of fuel transfer pump on side of engine block.                                                                     
The sensor on side of engine looks like round mushroom head with 3 wires molded into sensor, follow
the pig tail wire laying along side of valve cover on top of head zip tied in wire harness. Once finding
The triangle connector and disconnect from where it plugged into. At this point try to start the
engine, if engine starts and idle with the IAP sensor disconnect this would tell that the IAP sensor has
Failed. Dave Atherton Retired Cat Mechanic

Forget to mention you indicated boost pressure at zero (if this reading was at idle that’s the way it
It mentioned to operate and the atmosphere pressure shows 14 at idle which is normal


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