Upside triangle with decrease in MPG

[justmps01]

I have a 2009 IC CE300 DT466e and I get a upside down triangle warning light with “engine warn” driving at highway speeds(60-65mph). The bus then feels like it shutters, possibly out of overdrive and mpg decreases from >8mpg to mid 5mpg. No fault codes are active when running diagnostics. If I pull over and restart the bus, the indicator light is no longer on, and bus returns to it’s typical mpg of >8. If I continue to drive with the upside down triangle light on, the bus will return to its mpg of >8 after about 30 mins with the warning light never turning off. Any idea what this is?

[cadillackid]

no idea.. may have to read the codes with servicemaxx and then we have a much better shot at what it is..



if I had to guess id say that it gets an HPOP deficiency and runs at default ICP reading which is derated and will also hold the trans in lower gears.. but really your guess is as good as mine without fault codes..


my guess is that the dash wont tell us what the inactive fault codes are.. only active apparently..

[Sehnsucht]

What is your odometer mileage? When it shutters, does your engine RPM increase? If indeed it is downshifting out of overdrive, this is why your fuel economy drops if you're not reducing your speed in response. If you pull over and restart the engine, do you have to wait any amount of time or does it reset immediately?

Unfortunately the engine warn is just an idiot light to say there's a problem but offers no context. You're expected to have the right tools or a fleet maintenance or dealership plug in and read the engine code history to determine what happened. My concern would be it could be related to the diesel exhaust treatment system which is never an inexpensive repair. But it's basically impossible to know without reading the engine codes.

[justmps01]

The mileage is about 115000. I don’t actually recall what the RPM’s reading is when warning light kicks on, but I plan on taking out again to attempt to recreate the issue. However, when I pull over and restart the bus, it resets immediately. I seems to trip the warning light about every 3 hrs of straight highway driving.