P203B code 500 miles in

[Grinks22]

I was on my way home from work today and the check engine light came on. I noticed on my iDash that the DEF level was at 0. That percentage has never been a constant reading on the iDash display, it is always bouncing between 0 and what I thought was an accurate reading. Does anyone else have the iDash and have it setup to display the def level? And if so, is your reading constantly displayed or does it bounce like mine did/does? Looks like the code is redundant level sensor. This is on the baby max, not the big boy. Probably end up getting a new def tank, looks like the sensor is part of the tank itself.

 

[AXE]

Someone said there is a float inside the tank too, but not sure. I have replaced DEF sensors in my previous 2500. Did not have to replace the tank then.

 

[securityguy]

I was on my way home from work today and the check engine light came on. I noticed on my iDash that the DEF level was at 0. That percentage has never been a constant reading on the iDash display, it is always bouncing between 0 and what I thought was an accurate reading. Does anyone else have the iDash and have it setup to display the def level? And if so, is your reading constantly displayed or does it bounce like mine did/does? Looks like the code is redundant level sensor. This is on the baby max, not the big boy. Probably end up getting a new def tank, looks like the sensor is part of the tank itself.

I have one and it's fairly steady. Never showed a ZERO at all. Mine is on the 6.6L.

 

[Grinks22]

Hopefully it’s a simple sensor replacement or recalibrate the sensor. I didn’t look to far into it. I’m thinking it has been messed up since I bought it, if your gauge isn’t doing what mine was doing or it could be the difference between the little guy and the big guy’s sensor. Time will tell. Thanks for the response.

 

[AXE]

Also, I was on a long road trip this summer on my 2500HD. I got a DEF low message twice after adding a 2.5 gallon jug and then it would disappear. I am certain I had at least 3 gallons both times.

 

[Grinks22]

I didn’t even get that message. I just noticed on my iDash that it was at 0, then saw the check engine light, the checked the trucks display and it said no def information available. I was surprised I didn’t get the low warning message.

 

[KLA]

You're lucky it didn't de-rate the motor.

 

[AXE]

You're lucky it didn't de-rate the motor.

That's why you carry an OBD II, to clear codes and keep rolling. I did that on my last 2500HD.

 

[Grinks22]

The old girl is going in Monday morning. Hopefully it doesn’t decide to de-rate before then or I’ll try Axe’s trick of clearing the code and keep rolling. Probably won’t drive it much anyway until Monday. A lot of Banks haters out there, it the iDash gauge is a pretty nice tool to have in your truck. Nice to be able to keep tabs on things going down the road.

 

[KLA]

That's why you carry an OBD II, to clear codes and keep rolling. I did that on my last 2500HD.

That's a good idea, but on our Mack Tri Axles at work, certain codes, when cleared won't stop the .motor from going into de-rate mode and need to be sent to the dealer to clear the codes and re-set the ECM. Hope the Duramax isn't like that.

 

[LSnTX]

Yes, I have an idash and DEF level will vary as it gets lower as you would expect. Not 0 to ?, but something in the range that is in the tank. I believe sensors can be replaced if that’s what’s needed and not the whole tank. Keep us informed
I might ask how low you think you were before it gave code?

 

[Grinks22]

The iDash always bounced from 0-95 when I installed it, spent more time at 0 than at the tank level. The truck gauge in the dash never came off of full. The last number that popped up on my way to work was 78. Then it stayed at 0 and the CEL light came on. I’m thinking the sensor was malfunctioning from the beginning. I thought I read it was the whole tank, but after AXE said just the sensor can be replaced, I think you guys are right.