DEF tank full, gauge blinking red, coach will not start

ggangl1 · 07-08-2021, 07:14 PM

Filled up my DEF tank, but the DEF fuel gauge is blinking red and my coach will not start. 2014 Thor Palazzo.

Thanks

ggangl1 · 07-08-2021, 07:15 PM

I did disconnect battery for 20 minutes.. but the problem still occurs.

**EA37TS** · 07-08-2021, 09:57 PM

Did you run it out of Def to where it went into limp or shutdown mode. If so you might need a Freightliner or Cummins reset by the dealer.

TurnerFam · 07-08-2021, 10:26 PM

in 110,000 miles in our 2014 Palazzo, I've never run into that problem. The RED means that it 'thinks' your DEF is absolutely OUT, even though you've filled it.

Now, clarify what you mean by 'the coach won't start'... do you mean it turns over but yet won't crank, or that it just does NOTHING when you turn the key?
Did you hook up the battery cables correctly?

Try to Use the 'Emergency' or 'AUX' switch on the dash: HOLD it down, then try to crank over the diesel, while CONTINUING to hold the switch even after it cranks. This ties the two battery banks(Chassis and House) together to help make sure you have enough 'ooomph' to crank it.

If not, it sounds like the DEF 'SENSOR' is not yet reading properly. You may have to actually unplug the sensor, somewhere on the tank, and see if it resets it.

ggangl1 · 07-08-2021, 10:31 PM

Don't think so. I filled up the DEF tank. took about 4 gallons to fill.

Thanks for the repley

ggangl1 · 07-08-2021, 10:33 PM

It turns over just fine.. Just will not start.

TurnerFam · 07-08-2021, 10:52 PM

hmmmm, I'm not sure the DEF level would keep the engine from starting, so it sounds like maybe a coincidence that it happened right after filling the DEF? Who knows. Is it out of diesel? How 'long' are you turning it over? How long do you allow it to be in the 'ON' position to prime the gloplugs before trying to crank it?

Bob Denman · 07-08-2021, 11:14 PM

Could the DEF have been too old to be useful?
I have heard that it deteriorates over time...

lwmcguire · 07-09-2021, 09:57 AM

Turner is right, it should start but not allow you to go over 5 mph or fast idle

You would have a grid heater rather than glo plugs which should be cycling

If not then you have other issues

Did you turn your chassis battery disconnect switch or physically remove a cable?

Need more info

**EA37TS** · 07-10-2021, 01:44 AM

Similar issues came up during the Cummins Maintenance Seminar today. A few years ago there was a round of bad DEF sensors that were installed. According to C Cummins if the DEF reads empty and the gauge does not reset after filling it could be (operative word "could") a bad DEF sensor. That's as far as the topic went because the seminar came to an end.

Wandering · 07-17-2021, 09:27 PM

My understanding is that the DEF doesn't go into the engine itself, but into the exhaust treatment system. So it shouldn't affect the engine other than maybe messing with exhaust back pressure - unless the engine computer won't let the engine run due to logic associated with the DEF system. Since the computer lets the engine turn over, I suspect that it's not a DEF issue. Unless the exhaust treatment system is now blocked or nearly blocked, so that the engine can't push exhaust out. That'll sure prevent it from running!

lwmcguire · 07-18-2021, 12:01 AM

Quote:

Originally Posted by ggangl1

It turns over just fine.. Just will not start.

Check your fuel filters and since you haven't been back it must have started

**EA37TS** · 07-18-2021, 12:06 AM

Def blinking red will derate performance and prevent starting depending on the def issue.

Have you read the fault code? The code will tell you what’s wrong.

Also, which engine light is on, amber or red? If none you may have a stuck float at empty preventing you from starting. If it won’t start you might not get a code or engine light.

You may also like: