Technical map sensor failure-new cause?

[allant]

map sensor where to buy

hi
problem on stilo 1.6 active
had the eml come on, got the rac out who ran their diagnostic on the engine come back with 3 codes
p0571 brake switch malfunction
p0460 fuel level sensor malfunction
p0105 map sensor
ignoring the first 2 errors, is it a stright forward replace map sensor, or is there more to it.
car is a 52 plate had no problems upto today. have read other posts which state it requires software update but it has ran well up to this episode on the old software. so why should it need the new to cure it.
if it is software how much roughly do fiat charge for this and where is the best place to buy a new map sensor, direct from fiat or is there another supplier
what sort of price will the mp sensor be.
if fitting a new map sensor will this clear the warning from the dash
thanks

 

[Deckchair5]

Re: map sensor where to buy

P0105 doesn't mean you need to replace the Map sensor. They're very reliable and rarely need replacing
Always do a search before opening your wallet
https://www.fiatforum.com/stilo/178645-p0105-1-6-16v.html

 

[allant]

hi
rang fiat dealership about price for replacing map sensor (see earlier post)
chap at fiat says it might not be map sensor, as others on forum have said, and that it could be a software update is needed. he also said, which is the first time i have heard this mentioned, that if the oil is overfilled it can then get pulled up and into the sensor which triggers the eml.
anyone else heard of this.
prices quoted
£50 diagnostics
£140 map sensor fitted
all plus vat of course

 

[Argonought]

Keep posts together. If you can't be bothered to find an old post then what makes you think anyone else will

Now merged for you.

 

[Deckchair5]

he also said, which is the first time i have heard this mentioned, that if the oil is overfilled it can then get pulled up and into the sensor which triggers the eml.
If you overfill your engine with oil it'll more likely blow the crankcase seals out requiring complete engine strip down but being pulled up and into the MAP sensor? You could coat your MAP sensor with oil and it wouldn't bat an eyelid. It's a pressure sensor like a burglar alarm door mat, you can cover it with a carpet and it couldn't care less

 

[NumanR]

Not true decks, there is a service news regarding this, and oil coating is a major cause of the p0105 error, its not the fact that the sensor misreads the pressure, the problem is the speed of change of signal, when you coat the sensor with oil, the signal radically slows in its change speed, so its reaction time increases so the ecu reacts slower to pressure changes in the manifold. Fiat now recommend to keep the oil level 2 mm below max, when I get a P0105 error, I ask the customer two questions, has the vehicle recently had a service? And has it had a cambelt changed recently?

 

[Deckchair5]

Interesting. How is oil, sloshing about in the crankcase, rising and falling by much more than 2mm on every corner I would have thought, going to find its way up to the inlet manifold and onto the MAP sensor?

It's got a protective cap on it so the sensing element is totally shielded from the environment it's sampling. The MAP sensor should be totally unaffected by oil. Bosch think so
http://www.bosch.com.au/content/language1/html/4596.htm

A build up of hard deposits - the same as the inlet valve - I could go with but oil on its own?

 

[allant]

hi
deckchair5, my thoughts entirely.
i would of thought even if the oil level was unduly high that it would blow a seal somewhere to relieve the pressure. to get up to the map sensor it would have to get passed the piston rings and then up past the inlet valves. all the time the engine is doing it usual stokes, suck, compress, bang & exhaust. so to pass the inlet valves it would have to do it on a suck stroke when the inlet valves are open. highly unlikely i would think.
the only other way is by a crankcase breather pipe feeding back into the inlet manifold which is more feasible.
took map sensor out today to check, no sign of any oil or other contaminants on sensor.
checked oil level, which is high but not over filled.

 

[Deckchair5]

Have you manually cleared the fault code with a fault code reader or similar? It will go on ignoring the MAP forever whilst the fault code is stored and will give you dire mpg whilst it's there

 

[allant]

hi
mpg in the low 20's
fault code not cleared yet, i don't have a code reader yet. it's going into garage either today or tomorrow, told garage problem, not a fiat dealership. they say they will put on diagnostics again to check code, fit new map sensor if required, clear code. all for £115, to do it myself the best price i have found for a new map sensor is £115 but if i do it myself it would not be able to clear the code and would have to take it in to a garage for them to do, so would probably have to pay around £50 for them to clear it.
good news to follow hopefully.

ps. after this i need to get a code reader. which is the best code reader to go for a hand held unit or a pc based one.
thanks

 

[Deckchair5]

It would be far cheaper to have bought a £30 fault code reader and clear the code yourself. You would also have the reader for future use so a sound investment.
There's no reason to need a new MAP sensor unless the existing one is proved to be faulty. They are extremely reliable units and can be checked electrically

£30 < £115 + £30.

If you go the whole hog and get laptop based equipment you can SEE how your MAP is responding but I can't advise you on what's best as they keep updating, getting better and better. Check out Ebay perhaps

 

[allant]

hi
deckchair
can a ordinary garage with normal diagnostic equipment check out the map sensor or does have to go into fiat or to a specialist diagnostic provider.
thanks

 

[wvam]

(1.6 Dynamic '52) Well I bought a £30 U480 code reader and it was money well spent. It also allowed me to clear some old codes from the previous owner and get back to square 1. So I would recommend some spends on one of these.

The curious bit was I couldn't cancel the dash saying "Stop Engine", even though I had cleared all the codes! I also had the seat belt light on. Cleaned all the contacts under passenger seat, seat belt light went off . Re ran the codes - nothing there but, engine stop message went away!

At the moment, no codes, no lights, no messages - fingers crossed.

So I'd go with the previous advice and buy a code reader.

 

[allant]

hi
i have done a search of the forum for a map sensor wiring diagram, which has come back empty.
has anyone got a wiring diagram for the map sensor and info on what voltages to look for under the different operating levels.
i have the workshop cd but it is acting up has i can't get into the wiring section
thanks

 

[Deckchair5]

Bosch tech specs here but that's a bit over the top for what you'll want


http://www.bosch.com.au/content/language1/downloads/Map_Sensor_Technical_Specification.pdf


Best way is watch what it's doing on a trace v rpm

Here's a good MAP sensor (mine)
Warm engine- tickover-sudden blip to 2500 rpm - steady state- back to tickover
see how the MAP reacts quickly to sudden throttle response. Less pressure at higher revs steady state- then back to tickover

Quick response up and down
What would be bad? Flat line, slow reaction, sticking

You can check it in action by backprobing with a voltmeter but you're better off with one of the old analog types so you can see the speed of change

But what you want to do first is what I've already said. Clean the contacts, clear the fault code and see if it now likes the setup. If it's happy now then job done, if it isn't it'll tell you.

 

[allant]

hi
i have cleaned the contacts and also removed the sensor to check it's not visually broke and no oil or contaminants on it.
before disconnecting the sensor i disconnected the battery and left it off for a few hours before reconnecting. then started engine, eml on. took car for a few runs as someone stated that after a few engine run cycles the eml would go off if problem cleared. still on.
so it looks like i need a code reader, to clear the code.
thanks

 

[A3jeroen]

Hi. Clearing the code is done by starting the engine with the MAPsensor unplugged, stopping the engine, plugging back in and starting 3 times (found that on this forum IIRC).
If you really need a sensor, I have one lying around cause my problem wasn't MAPsensor related after all. Shoot me a PM if you want it.

gr J

 

[allant]

hi
things looking good
cleaned sensor connections and then checked i had 5v at sensor feed connection, reconnected plug, started engine then checked voltage at the variable voltage connection. all seemed ok . only problem was with my multimeter, voltage range is 0-2 then 2-10 so bit of guess work but a definate voltage change when increasing and decreasing throttle position.
i have purchased a hand held code reader (u480) plugged in and turned ignition on, read error codes and then erased them, message returned, erase done. disconnected reader and started engine, mil no longer coming on. took car out for a couple of runs stopping and restarting engine. all ok.
thanks deckchair5 and others for the help.

p.s. just changed brake switch. so another job done. just got to let the cuts and scrapes on my hands heal now.

 

[Deckchair5]

Ah that's good
You'll use the U480 many times in the future so it's a sound investment and a lot cheaper than the £115 you were stating earlier

 

[NumanR]

There are two pipes, which the breather system use to deliver crankcase gases up to the inlet mainfold, there is an oil trap in the large one. These pipes can transfer oil into the inlet manifold as a mist and coat the inlet pressure sensor.
We have also found incorrect valve timing (even slightly) can also cause this error, as can a lambda sensor, also a fault with the a/c pressure sensor or its wiring can also cause this fault as the wiring is interconnected.