Technical P0105 & p0340

[chicken_chau_mein]

My car does have air con but its very intermittent. It works when it wants to. Normally only when the engine has warmed up but then, it still doesn't always work. I have a malfunction code for the air con too but i'm ignoring it as the engine issue is more important!

Erm... Where's this new switch...?

Cheers decks. I'll check that out very soon.

 

[sixpotman]

Could be the one down on one of the pipes which goes
in and out of the condensor radiator at the front
of the car.

John

 

[Deckchair5]

My car does have air con but its very intermittent. It works when it wants to. Normally only when the engine has warmed up but then, it still doesn't always work. I have a malfunction code for the air con too but i'm ignoring it as the engine issue is more important!

Ha! Now you tell us Probably just low pressure, what fault code is it?


Air con pressure stat is down here ( see the connector spring catch behind the pipe in the pic?) but you can reach it from top side, standing at front of car, reach down the lh side of radiator and it's at the bottom, spring catch on the side of the connector, release wiring from harness clip and it's easily long enough to view from topside as shown in photo above

When you check for 5v at the pressurestat then check again for 5v at the MAP whilst the pressure stat is disconnected just to see if the pressurestat is dragging the voltage down

 

[Shadeyman]

If the presure sensor is giving a low reading because its faulty and you've checked the presure is correct manually with a gauge, is there a way to engage the clutch on the pump?

 

[Deckchair5]

Sure, just simulate a good pressure with a voltage midrange between 5v and 0v down the pressurestat signal terminal. Two resistors joined together and a midpoint take off to give a voltage split of 2.5v will do the job but don't install permanently as high pressure sensing is needed to turn off compressor and switch on the rad fans

 

[chicken_chau_mein]

My car does have air con but its very intermittent. It works when it wants to. Normally only when the engine has warmed up but then, it still doesn't always work. I have a malfunction code for the air con too but i'm ignoring it as the engine issue is more important!

Ha! Now you tell us Probably just low pressure, what fault code is it?

View attachment 91167
Air con pressure stat is down here ( see the connector spring catch behind the pipe in the pic?) but you can reach it from top side, standing at front of car, reach down the lh side of radiator and it's at the bottom, spring catch on the side of the connector, release wiring from harness clip and it's easily long enough to view from topside as shown in photo above

When you check for 5v at the pressurestat then check again for 5v at the MAP whilst the pressure stat is disconnected just to see if the pressurestat is dragging the voltage down

Sorry lol, i didn't think it would have anything to do with the engine problem. Anyway heres a readout from my diagnostics with the engine off but set to mar:

With the ignition off, it allows me to clear some of the codes and i'm left with these:

Anyways, i've checked out what you told me and everything is correct. There is a 5v at the new switch. With it disconnected, there is a 5v at the map sensor but once plugged back in, the map sensor is getting 0.14v again.

I had my air con "fixed" a while ago and they told me there was a circuit problem back then and they fixed it. They didn't really though. Only a few weeks back i checked the pressure of the air con and it was zero so i topped up and it worked! Its still intermittent but its not very hot so it doesnt get used often.

Can i just mention, why do you think i've got this problem? The previous night i topped up some oil and also had a long drive to london and back from manchester doing above motorway speeds. It was only the next morning that my car surfaced this error and it was impeccable beforehand. :bang:

 

[Deckchair5]

Aha! Ok looks like there's something up with the pressure stat.That's what your car has been telling you all along but you didn't tell us!
Disconnect the air con pressure stat and leave it disconnected, it is dragging down the 5v supply line, clear the fault codes and then see if your MAP and CMPS are now fine with no more relevant fault codes, if they are then it looks like you may need a new aircon pressure stat and that's all.

But don't just rush out and buy one, they're expensive, there may be a simple fault in the wiring to it. See how you get on and post up your findings

 

[richydraper]

and for got sake if it is the A/C sensor dont rip it out without getting the system vac'd beforehand

 

[chicken_chau_mein]

I LOVE YOUUUUUUUUUUU!!!! With the switch disconnected, cleared the fault codes and started her up. No more beep beep beep! Check is ok and the only fault code i'm reading now is the P0530 air con bla bla bla. Stepping on the gas pedal felt like it was a whole new car... She's got power again!!!

I can live without air con for a while. Just out of curiosity, how much is a new switch and how easy to replace?

And where do you live so i can come down and buy you a drink mate!

 

[Deckchair5]

Ha! Good stuff.

It's very easy to replace the aircon pressure stat, no need to vac down the system as there is a schrader valve in behind it so you just get a "pssst" and that's it, you're not going to damage the ozone layer
You just unscrew it and put the new one in

It's around £30. But you can do some simple resistance checks on it first. Between the two outside pins 1-3 the resistance should be around 54Kohms. The resistance between 1-2 and 2-3 should add up to the 54kohms so 1-2 might be 42kohms and 2-3 might be 12kohms
42+12=54kohms you get the idea?

Feel free to donate a very small portion of what you think you've saved to the forum to keep it alive, that'll do everyone more good including me as I've been on the wagon now for 10years

 

[chicken_chau_mein]

Hey again decks, having the car back to normal was good except for one thing, she drinks alot of fuel!

I did have a go at checking out the resistance on the stat but it didn't come up with the figures you listed in any combination of the three pins.

You mentioned it would be about £30 to replace but exactly how easy is it to change?

And yes i know that £30 is gonna be way off the current price but theres no harm in asking...

I've had a look on eper at the aircon page and i've identified 2 possible pressure stat's. If you could point me in the direction one more time...

 

[Deckchair5]

The items that have most influence on mpg are MAP and then lambda sensor because they are determining the air/fuel mix. Lambda when rpm is steady and MAP everywhere else.

First thing to try is easy and you are simply telling the ECU to recalibrate itself for the MAP. Disconnect the MAP, start the engine. This will give a P0105 MAP and P0101 air temp error. Reconnect the MAP, clear the fault codes and then turn key to MAR and leave 10secs then turn key off and wait 10secs whilst it stores the atmos pressure. Then start engine with aircon off and let it idle so it checks idle vacuum pressure and take it for a drive. It will recalibrate itself and check the max and min values of the MAP. With mpg of around 25mpg then this is the most common cause.

Then look at your lambda readings at warm tickover, look for it flip flopping 0.1v to 0.8 every sec.
Next big influence is engine not getting up to temp ie wide open engine thermostat. Feel the pipe from the thermostat to radiator, it should remain fairly cool until the engine gets up to normal temp

OK Air con pressure stat.

The fact your pressure resistances don't look right ( but bear in mind figures will be different with it connected and gas pressure pressure on it but should still add up ie A+B= C every time) and as soon as your connect yours the 5v rail system collapses shows a failed component there
I had a look back at my receipts and I bought one for Stilo 1.6 in Jan this year Part no 0051768498 price £39.47 inc VAT.
It's very easy to change, easier than changing a spark plug except you need to get underneath the car. Just disconnect the electrical connector, undo the sensor, be prepared for a slight psst of gas and then fit the new one. Easy as that

You can get them elsewhere
http://www.autoairconparts.co.uk/fiat-stilo-air-conditioning-pressure-switch/
but Fiat dealer Simonstone Bristol was cheapest for me

 

[NielsBoersma]

Hello everyone,

I would like to start with apologizing for digging up an anchient thread like this. However, i just created an account for the sole purpose of doing so.

I felt a strong urge for thanking everyone who has contributed to this thread, as it described and helped fix the exact difficulties i experienced with my 1.6 16v stilo.

Especially Dr.Decks's patience in diagnosing and percise step by step explainations have enabled me to fix my stalling engine and my AC in one.

Last week on my way to work my engine stalled like when you accidentally go to 1st gear while driving. From then on did not seem to respond on any gaspadle inputs.
A friend helped me tow my car back home and i went on getting one of those bluetooth OBD readers. P0105 and P0340 came up and also the P0530 for AC pressure malfuntion showed. As the AC had not been working for months i just took P0530 for granted and googled 105 and 340. This thread came up first. I was amazed reading about the AC error on Page 3 and all pieces of the puzzle became clear.

I literally ran to my car, unplugged the AC sensor and BAM the engine was working again! I went on and drove to a junkyard where i found a totalled, mostly disassebled punto with the LPS still there. I was able to buy it for 10 euros. I switched sensors in about 5 minutes and BAM, cool air was flowing once again through my dear stilo.

A warm fuzzy feeling came over me as i just fixed my first serious break down, all by myself! (Actually with alot of help from Dr.Decks, but hey!) Its hard to overstate my satisfaction.

I could not have done it without this thread and i expect it would have cost me more than 10 bucks at a garage!

Thank you so much!

I will be finding my way to the donations secion now.

All the best from the Netherlands,

Niels

 

[Alex07fiat]

You are the man!!! Deckchair5!!! :slayer::slayer::slayer:

I had same issues with my car.
Max. 3700rot/min + p0105, p0340.
Changed MAP and camshaft senzor with no results.

I had my Stilo in Fiat service and they didn't knew what do to... ))