Engine Light Coming on and Off

[Booneandthebus]

Hey there!

I’ve had my yellow engine light come on and then go off a few seconds later a few times today. Don’t have a code reader, but the condition is very specific so I wanted to see if anyone had insight.

The light will come on for a few seconds when I’m going downhill at 60+ mpg, with RPMs around 2400. Then goes off. It is somewhat repeatable on downhills.

Everything feels normal. Gauges reading normal. Not losing power. Any thoughts on what this could be?If I get a code reader will the engine code still be there, even thought the light is off?

(Engine is a 2006 DT466, with an Allison 2000 transmission. I replaced the EGR cooler with a bulletproof EGR cooler in hopes of preventing any big issues there. The bus has so far been super reliable and taken us all over the country.)

[TheHubbardBus]

Originally Posted by Booneandthebus

The light will come on for a few seconds when I’m going downhill at 60+ mpg, with RPMs around 2400. Then goes off. It is somewhat repeatable on downhills.

The light is telling you someone swapped your bus for a prius when you weren't looking

Seriously though, I don't know, but if I were in your shoes my first suspicion would be maybe you're hitting the governor / rev limiter?

[musigenesis]

You can read any codes without a scan tool. Turn the key to the ON position then press the diagnostics button (which should be on the underside of the dash beneath the gear shifter, next to the data port). The yellow engine warning light will then flash in sequences of three, kind of like Morse code, for each code. Example: flash flash pause flash pause flash flash flash longer pause flash pause flash flash pause flash flash flash would indicate codes 213 and 123. You can then find a copy of the code table online to tell you what the problem is.

[Booneandthebus]

She's trying her best! I'm glad she'll do above 55 mph haha. Got the electronic speed limit removed (set to way faster than I can go, according to the mechanic...). Any idea if the rev limit would be in that range? I've definitely had it go higher. But she does have smaller drive tires and highway speeds are some of my worst mpg. Pushing 2500 rpms quite often.

[Booneandthebus]

Originally Posted by musigenesis

You can read any codes without a scan tool. Turn the key to the ON position then press the diagnostics button (which should be on the underside of the dash beneath the gear shifter, next to the data port). The yellow engine warning light will then flash in sequences of three, kind of like Morse code, for each code. Example: flash flash pause flash pause flash flash flash longer pause flash pause flash flash pause flash flash flash would indicate codes 213 and 123. You can then find a copy of the code table online to tell you what the problem is.

I will give this a try! Thanks for the instruction! I'm pretty used to the OBD II setup for cars, but definitely have some learning to do on the bus side of things.

[cadillackid]

on a 2006 the display cluster should have an LCD panel in the cluster. you should be able to turnb the key on and press the "cruise on" and "resume" at the same time and release.. the codes should display in the LCD panel..



my guess is that if this is happening under Load when pushing it that its going to be an HPOP related code indicating an ICP / IPR issue (or posisbly weak HPOP).. these are what i see most often when someone says a code displays when pushing the engine hard and then it goes away after slowing down.. but no way to know till you read them out

[HamSkoolie]

Check your fluid levels....oil, coolant, transmission


Not likely but since it is only when going downhill it could be that fluids are at an insufficient level in that condition (I have seen this happen)


Also, you said it happens when your careening downhill (okay my word). Does it happen if you reduce speed and rpm?

[Dbacks2k4]

I've seen an intermittent warn engine light on 2006 Dt466e's be a failing turbo as well as what others have said... IPR, HPOP, etc. Definitely advise to get code reader or servicemaxx on it to see for sure.

[cadillackid]

Originally Posted by Dbacks2k4

I've seen an intermittent warn engine light on 2006 Dt466e's be a failing turbo as well as what others have said... IPR, HPOP, etc. Definitely advise to get code reader or servicemaxx on it to see for sure.

I always forget in 06 they had the VGT turbo by then.. and that actuator sticking was a known failure point.. good call on something else for him to check!

[Dbacks2k4]

Originally Posted by cadillackid

I always forget in 06 they had the VGT turbo by then.. and that actuator sticking was a known failure point.. good call on something else for him to check!

Yep much as I love the 2004-07 466 overall the turbo on the pre-04 was so much more reliable (and cheaper to replace) lol

[cadillackid]

Originally Posted by Dbacks2k4

Yep much as I love the 2004-07 466 overall the turbo on the pre-04 was so much more reliable (and cheaper to replace) lol

and it only got worse.. the 2010+ Maxxforce DT with compound turbos was terribler than this one

[Dbacks2k4]

Originally Posted by cadillackid

and it only got worse.. the 2010+ Maxxforce DT with compound turbos was terribler than this one

Don't I know it... the only maxxforce I ever had the displeasure of owning was a 2008 maxxforce dt and ironically the only thing that didn't fail on it during my ownership was the turbo... Sold it off 3 years into owning it when the emissions system started imploding on itself. Second worst bus investment I ever made as an uneducated novice... Worst was a 2005 vt365... Fortunately my mechanic sat me down and gave me a good education before I ever made a maxxforce 7 mistake

Sharing these experiences are why I'm now banned from most Facebook bus sales groups lol

[cadillackid]

Originally Posted by Dbacks2k4

Don't I know it... the only maxxforce I ever had the displeasure of owning was a 2008 maxxforce dt and ironically the only thing that didn't fail on it during my ownership was the turbo... Sold it off 3 years into owning it when the emissions system started imploding on itself. Second worst bus investment I ever made as an uneducated novice... Worst was a 2005 vt365... Fortunately my mechanic sat me down and gave me a good education before I ever made a maxxforce 7 mistake

Sharing these experiences are why I'm now banned from most Facebook bus sales groups lol

the VT365 is a double edge sword.. it actually is a great engine.. as long as you Build it before it breaks ...



as for the 08 maxxforce that still has the same style turbo you have now.. they didnt go to the compound turbos and Common-rail injection until 2010.. the Maxxforce of course did get a DPF and the way navistar tried to handle regen was a disaster and resulted in a lot of melted pistons or broken skirts.....


the maxxforce 7.. ha! well.. yeah.. actually once the redesigned pistons came out for the 11/12 model year they got better.. but you really still needed to deal with the inherent crappy oil and EGR coolers those engines STILL got (even after the same debacles on the 6.0).. oh wait yeah then the nuking injection pumps sending schrapnel into those expensive piezo injectors.. scratch that the MF7 really never did get better...

[TheHubbardBus]

So did you pull the codes, OP?

What did you find?