CEL 206D?

[Rusty PW]

Has anyone have come across this code of 206D? I'm at Rausch Creek. I cleared it with my iDash gauge, and it hasn't come back. Funny thing is. My DEF level went from 3/4 full to full reading.

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[DylanM]

Running through the service manual, it says the DEF tank has a "Quality Sensor" that measures the concentration of the DEF ultrasonically and also measures the DEF temperature. It'll throw your P206D fault if the concentration measures high (greater than 62.5%) and the temperature is above 409°F. If the sensor cannot read then the scan tool readout will show a default of 399.9%.

Possible causes are contaminated DEF, frozen DEF (guessing this isn't it at this time of year), old or stagnant DEF due to extended storage time, DEF aeration due to rapid temp/altitude change or refill, or a faulty sensor. I would guess the aeration issue could also be caused by bouncing around quite a bit offroad, but that's just a guess on my part -- that could also explain the increase in quantity reading IMO.

 

[Rusty PW]

Running through the service manual, it says the DEF tank has a "Quality Sensor" that measures the concentration of the DEF ultrasonically and also measures the DEF temperature. It'll throw your P206D fault if the concentration measures high (greater than 62.5%) and the temperature is above 409°F. If the sensor cannot read then the scan tool readout will show a default of 399.9%.

Possible causes are contaminated DEF, frozen DEF (guessing this isn't it at this time of year), old or stagnant DEF due to extended storage time, DEF aeration due to rapid temp/altitude change or refill, or a faulty sensor. I would guess the aeration issue could also be caused by bouncing around quite a bit offroad, but that's just a guess on my part -- that could also explain the increase in quantity reading IMO.

When the CEL popped on. I had just come through a rock garden. But that wouldn't explain the increase in tank level.

 

[Lost1wing]

Had it on my Duramax. Ended up being a sensor in the def reservoir. The sensor was fouled with crystallized def. I had a temp sensor fail that way, too. Several reductant heater failures over the years as well. I'm guessing you should be able to see the pressure with a scan tool. I'm not a fan of diesel emissions.

 

[Pliny]

The service manual has this:

Which isn't clear if there is a level sensor in the tank, as well as a level sensor in the supply pump.
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Did the DEF level go from 3/4 to full when you cleared the fault? Or was it that it went to full and then the fault happened?

 

[DylanM]

Which isn't clear if there is a level sensor in the tank, as well as a level sensor in the supply pump.

The DEF level sensor is in the pump, while the DEF quality sensor is nearby in the tank. I want to emphasize the fault code in question is actually for "Reductant Quality Sensor Circuit High".

When the CEL popped on. I had just come through a rock garden. But that wouldn't explain the increase in tank level.

I do still believe that since both the DEF quality and the DEF quantity sensors operate ultrasonically, and that the service manual states aerated DEF can cause an erroneous signal from the quality sensor, that it's plausible the quantity indication jumping up could also be caused by the same aeration/jostling of the fluid in the tank.

 

[GoatPowder]

While I agree that the QLS reads ultrasonically and the level is a learned estimate...

Isn't P026D 'Fuel injection Quantity Too High'? As in the emissions fault they started adding for increased fuel demand?

 

[DylanM]

Isn't P026D 'Fuel injection Quantity Too High'? As in the emissions fault they started adding for increased fuel demand?

Sure is, but the code the OP has a question about is P206D, not P026D.

 

[Vtur]

The DEF level sensor is in the pump, while the DEF quality sensor is nearby in the tank. I want to emphasize the fault code in question is actually for "Reductant Quality Sensor Circuit High".

I do still believe that since both the DEF quality and the DEF quantity sensors operate ultrasonically, and that the service manual states aerated DEF can cause an erroneous signal from the quality sensor, that it's plausible the quantity indication jumping up could also be caused by the same aeration/jostling of the fluid in the tank.

Do you know if the quality sensor replaceable?

 

[GoatPowder]

Sure is, but the code the OP has a question about is P206D, not P026D.

That it is, apparently I've gone dyslexic, my bad

 

[GoatPowder]

Do you know if the quality sensor replaceable?

It appears to be plastic welded in:

Though now that I've pulled the lil skid plate off, I can see where the harness could rub or get eaten by some trapped rocks.

If it trips for OP again might be worth pulling the plate and checking the harness (it's just 3 13mm's)

 

[Lost1wing]

I believe you guys with the ecodiesels will find out that you will go through plenty of DEF reservoirs if you hang on to your jeeps. The pressure, temp and level sensors tend to fail at the 3or4 year mark. On the Duramax, you can replace the temp sensor, but the price of the temp sensor is more than the assy. Otherwise I would attempt to clean the temp and pressure sensors. It's just not worth it when the heaters will fail in time.

The only solutions would be to replace the reservoir assy and check connections. One other possibility would be to drain the tank and add fresh DEF in case your tank was contaminated. The OP has a pressure fault so I even doubt that a flush will help.

If they ever get a reliable emissions system for a diesel, I would get another diesel. Mahindra has a few diesels that don't require DEF. They still have a DPF and EGR, but no DEF. I've never had an emissions fault on my Mahindra diesels.

 

[Rusty PW]

Thank guys. Love yinz.

 

[Rusty PW]

Tthink what I'm going to do when I get home js to remove the harness plugs. Clean them up. Apply di electrical grease and see what happens.

 

[Felinus Maximus]

I had this code pop up a couple of times on Gen 1 and Gen 2 Ecodiesel Rams. Cleared with BlueDriver, but came back. Both trucks resulted in warranted replacement of the entire DEF tank and pump, twice on the Gen 1 at around 30k and 60k miles. I think the Gen 2 was only like 18k miles when it happened. And, yes...I still drive EcoDiesels despite the gremlins. I'm a torqueaholic.

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