P20E8 error reset

[Gh5000]

Hi,

Had the p20e8 error pop up recently after getting the associated warnings on the dashboard. While waiting for the replacement OBD2 scanner to arrive off Amazon because I can't find my original, I topped up the adblue with around 8/9 litres. I did this while parked on a hill which I now read isn't best.

I've managed to clear the p20e8 error and have now lost the starting prevented in 700 then 600 miles messages. I'm presuming the error will return after some driving and I haven't fixed the problem with an adblue topup and a £5 scanner reset. My question really is with some Christmas driving coming up if the error reappears will I get the same few days grace again before starting at 700 miles countdown. Or will my countdown start from 600 again?

Not that getting out of a Glasgow to Bournemouth and back drive over a weekend isn't a bad thing. Just definitely don't want to be stuck there for Christmas!

Cheers

[GiveMeABreak]

The default countdown is when the range is 1500 or under.

When you start the ignition, if the range is greater than 1500 miles then there will be no range displayed by the spanner in the instrument panel.
Some later vehicles may constantly show the 1500 mile range until the actual range falls below this level, where it will then start reducing. So as long as it shows nothing or 1500 you should be fine.

On some vehicles depending on your instrument panel type, pressing the service button will usually show the status of the Adblue range (may take several presses to scroll - can't say for sure - or it may automatically cycle through).

[RichardW]

P20E8 seems to be low ad blue pressure. If the warning came on with 700 miles to no start then it's likely a fault, rather than just low level - as Marc says the top up warning usually comes on with 1500miles grace. If the fault has cleared, then if it comes back you will get back to 700 miles to go. In theory you can go on resetting the de nox system repeatedly, and you will get 700 miles each time.

Low pressure might be the pressure sensor, and there is a thread on here about repairing it.

[earlsgate]

yes you can clear the code with a fairly basic scanner but once the engine reaches a certain temp the error will reappear, if one of various conditions are not met, to prevent adblue system damaging itself . At some point you'll need to find out if the tank can be fixed or face buying an expensive replacement

A proper diagnostic should show some of the actual causes of the "low pressure", which in my case was related to the broken thermistor on the urea heating plate producing a default 0c temp reading for urea temp on the Denox readings. The recent Technical Service Bulletin "B1KW017XQ0" makes mention of this repair but as stated others have replaced the pump's pressure sensor and have kindly detailed all the necessary parts required

Not sure why yours produced a countdown situation whilst my P20E8 did not?