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Well it wasn’t the fuel filters….(to make a short story long)

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Rich W.

Retired Fire Chief
RVF Supporter
Joined
Jan 19, 2021
Messages
3,122
Location
Rosemary Farm, Grass Valley Ca
RV Year
2016
RV Make
Newmar
RV Model
Ventana 3427
RV Length
35
Chassis
Freightliner XCR
Engine
6.7 ISB 360/800
TOW/TOAD
2001 Jeep Wrangler
Fulltimer
No
Experiencing lower than normal boost (about 25% below normal) I was grasping at straws looking (hoping) for a simple, cheap fix. I didn’t really think it was the fuel filters (only 2300 miles on them) but I had spares on board and it was a possibility, and being a cheap and easy rule-out I gave it a try. Naturally no improvement from that but of course I pushed on anyway. Other than long grades and initial acceleration the thing ran fine and I was able to easily ramble along at 65mph.

Until the grade headed east out of Cheyenne. That was a long pull at the top of which I had a flashing amber check engine light, immediately followed by solid amber, solid red, and complete and sudden shut down, all within about 30 seconds, barely giving me time to get to the shoulder and stop, and all the while temp and oil pressure gauges reading normal. So after sitting less than a minute, baffled, I decided I had to re-start the engine to avoid hot engine shut down issues and it started right up. I put it in gear and it ran although obviously severely derated. Fortunately we were at an exit, with a small truck parking area on the side of the accompanying on ramp.

I parked, kept it running, and plugged in my trusty Diesel Handheld code reader and found SPN 5862 FMI 9 - Aftertreatment 1 SCR Intermediate Gas Temperature - Data Valid but Above Normal Operating Range. There is lot of info on this including three “possible“ causes in the library, none of which were correct. I’ll paste in the long version at the end of this post for anyone interested. The only other code was SPN 110, FMI 31 - Engine Coolant Temperature - Data Valid but Above Normal Operating Range. This seemed to be a result of the shut down as my temp gauge read normal before, and also normal immediately after re-starting, but was pegged momentarily while the engine was stopped - the reason I immediately restarted it. Interestingly this code also seems to be a clue to the actual issue (high exhaust temp) - more on that below as well.

I cleared the codes (there was no code indicating de-rate or anything else - just the two codes above) and we decided to move on down the road driving it as easy as possible since all indications at that point were that it was operating normally - no overheat, no recurring codes, etc. This seemed to be just another spurious mystery emissions glitch, similar to what many others have experienced. We stopped that night at the Cabela‘s campground in Sidney NE, everything still seeming normal. But the next morning we had a loud, screeching exhaust leak, apparently opening up after everything cooled. It was exactly one mile to Floyd’s Truck Service (we saw the Freightliner sign on the way in to the CG) so we drove straight there and are still here four days later and will apparently be here most of next week.

The Cause:
The apparent culprit is a leaking CAC causing the low boost I was experiencing, which I found inconvenient but unfortunately didn’t recognize it as a condition that could lead to bigger issues. The bigger issue is that it led to a rich fuel/air ratio because the engine was getting less air than it should but the ECM was still feeding it full fuel, which was everything it could since I was climbing a grade under load. The result was a very high exhaust temp even though the engine temp was normal. This warped the exhaust manifold beyond any point of re-surfacing, and of course I need a new CAC.

The only other pertinent info is that I had to do a forced regen early in the trip and that seemed like it was too soon since the last one, and later caught the system in the act of several active regens. This seemed weird but I chalked it up to a needy emissions system. The actual reason was excessive soot due to the rich fuel mix, but of course I never made this connection early on, just like I dismissed the low boost as troubling but not significantly consequential. Live and learn…

So I called Nappanee, cancelled my week at Camp Newmar, which was the reason for this trip, cancelled a bunch of other plans, boarded the dogs locally and we are currently holed up in a Comfort In owned by the Love‘s next door and across the street from Floyd’s. We have the Jeep and the bikes and are trying to make the best of it while we wait for parts. The shop is very professional, capable, and accommodating and provided a lot of info on fun and exciting things to do when stuck in Sidney Ne. What fun!

The Codes:
Fault Code: SPN 5862 FMI 16 (4525)
SPN: 5862
FMI: 16
Aftertreatment 1 SCR Intermediate Gas Temperature - Data Valid but Above Normal Operating Range - Moderately Severe Level
Reason:
High SCR Intermediate temperature detected.

Circuit Description:
The aftertreatment SCR (selective catalytic reduction) temperature sensor module is a smart device that communicates with the engine control module via the J1939 data link. The aftertreatment SCR temperature sensor module performs its own internal diagnostics and reports malfunctions back to the engine control module using the J1939 data link.

The aftertreatment SCR temperature sensor module is used to measure the aftertreatment SCR intermediate temperature and aftertreatment SCR outlet temperature. The temperature probes are permanently attached to the aftertreatment SCR temperature sensor module and can NOT be replaced individually.

The Engine Control Module (ECM) detected the aftertreatment SCR intermediate temperature was above 650°C [1202°F] for 60 seconds.

1. The ECM illuminates the red STOP ENGINE lamp immediately after the diagnostic runs and fails.
2. The engine will be shut down if the Engine Protection Shutdown feature is enabled.
3. Progressive power and/or speed derate increasing in severity from time of alert.
4. If the Engine Protection Shutdown feature is enabled, the engine will shut down 30 seconds after the red STOP lamp starts flashing.

The aftertreatment SCR temperature sensor module is mounted on the aftertreatment SCR catalyst.

1. To validate the repair, perform a key cycle, start the engine and let it idle for 1 minute.
2. The fault code status displayed by the diagnostic tool will change to INACTIVE immediately after the diagnostic runs and passes.
3. The ECM will turn off the red STOP ENGINE lamp immediately after the diagnostic runs and passes.
4. The Reset All Faults command in the diagnostic tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

This diagnostic runs continuously when the engine is running and active regeneration of the aftertreatment diesel particulate filter is not occurring.

Possible Causes of this Fault Code Include:
1. Malfunctioning fuel injectors
2. Malfunctioning aftertreatment SCR intermediate temperature sensor
3. Contaminated diesel exhaust fluid

Fault Code: SPN 110 FMI 31 (2646)
SPN: 110
FMI: 31
Engine Coolant Temperature - Condition Exists
Reason:
The EGR valve was closed to reduce engine coolant temperature.

Circuit Description:
The coolant temperature sensor is a variable resistor sensor and is used to measure the temperature of the coolant of the engine. The engine control module (ECM) supplies 5 volts to the coolant temperature signal circuit. The ECM monitors the change in voltage caused by changes in the resistance of the sensor to determine the coolant temperature.

The Engine Control Module (ECM) detected the engine coolant temperature was above a threshold and closed the EGR valve to reduce the engine coolant temperature.

1. The ECM illuminates the amber CHECK ENGINE lamp immediately when the diagnostic runs and fails.
2. Exhaust Gas Recirculation (EGR) valve operation will be disabled.
3. Engine torque will be reduced if the engine is operated for an extended period of time with this fault active.
4. Possible reduced engine performance.

The engine coolant temperature sensor is located on the thermostat housing.

1. To validate the repair, perform a key cycle, and leave the key in the ON position for 1 minute.
2. The fault code status displayed by the diagnostic tool will change to INACTIVE immediately after the diagnostic runs and passes.
3. The ECM will turn off the amber CHECK ENGINE lamp immediately after the diagnostic runs and passes.
4. The Reset All Faults command in the diagnostic tool can be used to clear active and inactive faults, as well as extinguish the MIL for OBD applications.

This diagnostic runs continuously when the engine is running.

When the engine coolant temperature nears the engine protection limits, the EGR valve will be closed to reduce the coolant temperature. This fault code is used as an information fault code, ONLY indicating that the EGR valve has closed. No malfunction has occurred to cause this fault code. Other engine protection fault codes will be active if the engine coolant temperature has exceeded the engine protection limits.
 
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A couple conclusiions:

1. That exhaust temp gauge I’ve been considering would probably be a good idea
2. Frequent regens are not normal and probably indicate other issues
3. Since low boost is not normal, I should have cancelled the trip as soon as I noticed it and addressed that issue.
4. Since I had an engine overheat code (SPN 110) but the engine wasn’t overheating, I should have looked elsewhere for the cause, but didn’t dig deeper until after I had a warped exhaust manifold.
5. There were enough clues here that even if I couldn’t figure it out, I should have been more objective. The mechanic at Floyds knew the problem almost immediately.
 
Man…Rich..that is flat out UGLY!!!
When you said low boost and Check Engine light, I was really hoping it was what happened to me…a leaking CAC boot!!! I’ve had a coupe of those, and the latest was the turbo output boot. Those things get loose, and mine were all replaced a while back after my PDI work.

Sorry your’s was so much worse. I sure would like to know exactly how high your output and exhaust temps were during all this.

Maybe that mechanic can speculate. Since many of us run with a PDI Tuner, we have DPF, SCR, and PYRO gauges to keep an eye on. Never expect higher than 1100° pulling a grade and/or regen.

Sure glad you got good help, though, that’s more than half the battle!!
 
A couple conclusiions:

1. That exhaust temp gauge I’ve been considering would probably be a good idea
2. Frequent regens are not normal and probably indicate other issues
3. Since low boost is not normal, I should have cancelled the trip as soon as I noticed it and addressed that issue.
4. Since I had an engine overheat code (SPN 110) but the engine wasn’t overheating, I should have looked elsewhere for the cause, but didn’t dig deeper until after I had a warped exhaust manifold.
5. There were enough clues here that even if I couldn’t figure it out, I should have been more objective. The mechanic at Floyds knew the problem almost immediately.
Where was the CAC leaking?
 
Is the lengthly repair timeframe due to parts availability or tech availability? I would think exhaust manifold and CAC would be readily available.
 
The CAC appears to be leaking from the core somewhere towards the middle vertically and off to the drivers side a bit - when I went back over there Friday afternoon the guy who tested it had gone home for the day so I don’t know specifically - only that it was plainly audible from the radiator side - I’ll know more on monday.

The delay is for shipping. Apparently an OE CAC is no longer available and the after-market replacement has to come from either Minneapolis or Dallas. I talked to Superior Cooling in Austin today and they said I should be able to get it shipped in two days for around $200 but they couldn’t take an order until Monday.

I lost a couple days on this thinking the CAC wasn’t the problem (hoping it was a boot or clamp or something more common). It was finally tested on Friday afternoon proving it was. By then it was too late to order before Monday, loosing two days of a 3-5 day delivery time.

I should have listened to the mechanic (I’m going to have to ask him how he knew without testing it) but at that point it seemed more like an opinion, worst case, or flock shooting, and I didn’t want to wait for the CAC to ship here, or pay for a job I thought might not be necessary (kind of a big job for a rear radiator coach) and I still thought I could be back on the road by Friday afternoon. That was before my new exhaust manifold shipped to the wrong shop 215 miles east of here.

At this point I consider myself thoroughly defeated and at the mercy of the system/process although I will see about speeding up delivery (more $$) on Monday morning. Not much else I can do although I hear there is a nice Fall Festival in Dalton NE complete with an antique tractor pull. I’m also 0 for 3 on restaurants so far in Sidney with very few choices left and of course the coach is locked up in the shop. We did ride the bikes to Colorado through the corn fields for kicks.
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The CAC appears to be leaking from the core somewhere towards the middle vertically and off to the drivers side a bit - when I went back over there Friday afternoon the guy who tested it had gone home for the day so I don’t know specifically - only that it was plainly audible from the radiator side - I’ll know more on monday.
Thanks. I see now there are recommendations for annual pressure checks for CAC's. Some shops will do it free.
 
Thanks. I see now there are recommendations for annual pressure checks for CAC's. Some shops will do it free.
I never heard that and would not have expected that there was a need, but apparently this is not all that uncommon. I found some used “leaking” CACs for sale on line so apparently this isn’t unheard of. Looks like my old one is worth around $450.
 
I never heard that and would not have expected that there was a need, but apparently this is not all that uncommon. I found some used “leaking” CACs for sale on line so apparently this isn’t unheard of. Looks like my old one is worth around $450.
What's the failure typically, corrosion?
 

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