Disco 2 Ambient Air Pressure (Logged Low)

Hi you lot,

My discovery started bogging down on the way home today, seemed to have less boost. After checking hoses etc I used my trusty Nanocom and found a Code 2,8 Ambient Air Pressure (Logged Low)
Now, I know this is linked to the sensor in the air box, but can anyone tell me what it actually does and what the pressures mean? I checked the pressure with the nanocom and it was 104Kpa. Is this good?

Thanks you lot!

I believe it measures as it says, the air pressure. We normally consider this in milibars but you can check air pressure via metoffice weather stations nearby. 1020mb is 102kpa so that sounds fine to me. So i am guessing it is either an intermittent fault or it is a code associated with the map reading comparison to aap? But we know a man who will know : )

ronsealdeath said:

I believe it measures as it says, the air pressure. We normally consider this in milibars but you can check air pressure via metoffice weather stations nearby. 1020mb is 102kpa so that sounds fine to me. So i am guessing it is either an intermittent fault or it is a code associated with the map reading comparison to aap? But we know a man who will know : )

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Haha yeah, I thought as much, how does this effect the engine though, I mean why would it chuck up a fault I mean I could just be in a place with high or low pressure lol.
A new sensor is £30 in paddocks, might just change it but it would be good to know a bit on how it works, I have a stage 3 map on it too but it's never had a problem in 2 years so, can't be that lol.

Cheers Ron!

Hi, i presume your's is Eu3 engine if you found AAP/T sensor at £30... though i'd not put cheap sh*t there on a Eu3 engine, that sensor is too important to mess with britpart or other aftermarket stuff there, get genuine... in a nutshell: it's there for altitude compensation and boost management/overspeed protection but once the ECU stores a code on it the default is reducet boost, the basic description for it's pressure side is in the WSM but in reality it's more complicated due to the temperature component which is not described nor shown by diagnostics, explained here http://www.discotd5.com/td5-tuning/eu3-specific-limiters

You could try taking it out and cleaning it, or failing that buy a used one, these sensors aren’t prone to failing like the maf sensors, but if your feeling plush you could buy genuine new, but you will probably need to sell a kidney

They dont fail like MAFs but they wear out in time and the reading gets inaccurate, for Eu3 is not very expensive, the Eu2 is the killer.

sierrafery said:

They dont fail like MAFs but they wear out in time and the reading gets inaccurate, for Eu3 is not very expensive, the Eu2 is the killer.

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Thanks for the help! I found the sensor on Paddocks, but after talking to them it's for the P38, and they don't sell the one for my engine, it's dealer only.

I cleared the code, and today it was fine, no code either so I'm assuming it's either on its way out or a bad connection, dirty plug or something... I'll clean it all and check it all tomorrow and see how it goes lol.

P.S, sometimes on tick over it has some diesel knock, only sometimes... Could this sensor be causing that also? It did it before it was mapped also, so I know it's not due to the map.

Cheers!

If your's is Eu3 engine search for MHK100820L that's for Td5 no matter what suppliers say, if you dont want genuine at least get a branded one not britpart e.g https://twinwoods4x4.co.uk/product/mhk100820l-ambient-air-pressure-sensor-td5/ i dont think it has anything to do with diesel knock, that symptom exceeds my knowledge

sierrafery said:

If your's is Eu3 engine search for MHK100820L that's for Td5 no matter what suppliers say, if you dont want genuine at least get a branded one not britpart e.g https://twinwoods4x4.co.uk/product/mhk100820l-ambient-air-pressure-sensor-td5/ i dont think it has anything to do with diesel knock, that symptom exceeds my knowledge

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Thank you very much, I will indeed go genuine, I usually do apart from the injector harness I did get a britpart one of those lol. (I was skint at the time) and the oil was like a river flooding my ECU lol.

Anyway, cheers for the info!