Technical Dreaded P0101 mystery

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Technical Dreaded P0101 mystery

Griffj

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Apr 21, 2024
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Wrexham
Hello,
First technical Q.

Been having a long term problem with my daughters 500. (2014 1.2 lounge with 75k miles)

Started a few months ago with the usual "stop start unavailable" warning on the dash, lurked for an answer here.
Checked the battery to see it was the original, changed for a new dedicated stop start unit, prob went away.

Few weeks later, same warning reappears along with check engine, engine light and triangle. Read code, P0101, MAP sensor.
Changed it for a new Bosch unit, all good again for a few days, then same again, same warning, same code, only now car is going into limp after a drive (when idling after a drive, goes into limp after 2- 5 min). Read on here about the Evap solenoid. Got a new one from Italy, all good again for about a week then same as above.
Read about blanking off the Evap so tried that, all good again for about 2 weeks then normal service resumes with the faults. Now going into limp after almost every run. Still showing P0101 codes.
Read on here a thread about other things that can cause strange faults, so far I've changed,
Earth strapping under the battery for new,
Clutch position sensor.
Brake pedal switch.
Checked rear loom into boot, all good.

Any other thoughts on what to look for?

I'm completely out of ideas, so I'm paying £200 today for a full specialist diagnostic to be done in the hope something shows up!!
Will let you know.
 
Hello,
First technical Q.

Been having a long term problem with my daughters 500. (2014 1.2 lounge with 75k miles)

Started a few months ago with the usual "stop start unavailable" warning on the dash, lurked for an answer here.
Checked the battery to see it was the original, changed for a new dedicated stop start unit, prob went away.

Few weeks later, same warning reappears along with check engine, engine light and triangle. Read code, P0101, MAP sensor.
Changed it for a new Bosch unit, all good again for a few days, then same again, same warning, same code, only now car is going into limp after a drive (when idling after a drive, goes into limp after 2- 5 min). Read on here about the Evap solenoid. Got a new one from Italy, all good again for about a week then same as above.
Read about blanking off the Evap so tried that, all good again for about 2 weeks then normal service resumes with the faults. Now going into limp after almost every run. Still showing P0101 codes.
Read on here a thread about other things that can cause strange faults, so far I've changed,
Earth strapping under the battery for new,
Clutch position sensor.
Brake pedal switch.
Checked rear loom into boot, all good.

Any other thoughts on what to look for?

I'm completely out of ideas, so I'm paying £200 today for a full specialist diagnostic to be done in the hope something shows up!!
Will let you know.
Just had the full diagnostic done.

3 faults found,
Air leakage around intake manifold.
Ecu fault.
Stop start module false signal fault.

So, I'm assuming it's relatively easy to change the manifold seals?
Also can see its easy to replace the S.S module on the battery,
But, is the ECU interchangeable with other cars of the same spec or does it need to be coded or flashed to the car?
I've found a few new ones, all apparently for a 1.2, but all seem to have a different number, is this relative?

Thank you.
 
Best to get an ecu from the same model year/generation of car with numbers as c;lose as possible! either way it has to be virginised with all previous data removed so in effect a blank canvas! once installed needs matching to the other modules via software such as MULTI ECU SCAN!.
 
Best to get an ecu from the same model year/generation of car with numbers as c;lose as possible! either way it has to be virginised with all previous data removed so in effect a blank canvas! once installed needs matching to the other modules via software such as MULTI ECU SCAN!.
Ah. Yes, that was the plan to get one in that spec etc,
Was really hoping that wasn't the case with regards to programming etc, sounds expensive!
 
I'd only do the ECU after the other things, as it may be a knock-on error from the other faults. But if needed, the ECU may well be repairable by return post to a specialist, which would be plug and play - worth an internet search for repair companies. One known ECU fault is multiple misfire errors at higher speeds, which is one thing that can be fixed.
 
I'd only do the ECU after the other things, as it may be a knock-on error from the other faults. But if needed, the ECU may well be repairable by return post to a specialist, which would be plug and play - worth an internet search for repair companies. One known ECU fault is multiple misfire errors at higher speeds, which is one thing that can be fixed.
Already sorted bud, thank you.
The ECU is off to a specialist in Stoke on Monday for a brand new one to be cloned from it. Should be done and back on in about 3 days, he's also positive the SS fault is to do with the faulty ECU.
New manifold seals coming Monday as a precaution.
 
Already sorted bud, thank you.
The ECU is off to a specialist in Stoke on Monday for a brand new one to be cloned from it. Should be done and back on in about 3 days, he's also positive the SS fault is to do with the faulty ECU.
New manifold seals coming Monday as a precaution.
Well, that was interesting, been to the "specialist" in Stoke today, what an utterly dodgy setup, so much so I walked away, broken ecu in my hand, no way I was leaving it there. So glad I didn't post it as requested, not sure I would have ever seen it again.
That along with my order for the new inlet manifold gaskets being lost, its been a total loss of a day!
 
Hi ,

My first reply deleted

Apologies I 're read your first comprehensive post properly and see you have covered the points well.

I think you will have an air leak into the inlet manifold as suggested by another member.

Someone recently made their own smoke machine and used it to find an iffy inlet manifold to head seal , or two.
Best wishes
Jack
 
Last edited:
So, update.
Changed the intake manifold seals today, and while I could, cleaned the throttle body and replaced the seal on that too.

Cleared the codes, all was OK for about the first 20mins, S/S system working, no warnings, then once home, after idling for about 2 mins, all the warnings are back, same code P0101 shown again.
Im utterly fed up with it now, last thing I can do now is get the new ECU, and I'm really hoping that'll sort it, had enough of it, next stop is to find a Fiat 500 service specialist and get them to take a look I guess (won't use local dealers due to very bad experience with them in the past)

Anyone have any other ideas, I'll try anything!
So far it's had, new battery, MAP sensor, Evap solenoid, clutch position sensor, brake switch, and now intake seals.
Nothing has worked.
 
Check vacuum pipe to brake servo?
Plug the evap solenoid ..... someone posted earlier they replaced evap solenoid had same faults then plugged evap solenoid then no faults .
 
Check vacuum pipe to brake servo?
Plug the evap solenoid ..... someone posted earlier they replaced evap solenoid had same faults then plugged evap solenoid then no faults .
It's In my first post about that bud, already tried it.
 
Update on this fault.
The car is still giving me major headaches, still going into limp randomly when stopped after a drive, and no amount of diagnostic work seems to be able to pinpoint the fault.
But, we have noticed if the aircon is on, the car behaves itself, doesn't go into limp and all is well, but as soon as its turned off, limp returns within seconds.
Any thoughts?
 
The a.c. puts extra load on the engine so the ecu opens the throttle plate slightly to maintain the idle rpm. The effect of a slight air leak into the inlet manifold is similar to throttle plate being more open.
 
The a.c. puts extra load on the engine so the ecu opens the throttle plate slightly to maintain the idle rpm. The effect of a slight air leak into the inlet manifold is similar to throttle plate being more open.
Could you explain a little more?
Cheers.
 
Could you explain a little more?
Cheers.

If there is still a slight air leak into the inlet manifold when a.c. is on the leak is less noticeable to the ecu because the engine has to work bit harder to power the a.c. compressor.[/QUOTE]
 
Thanks for that.
Inlet manifold gaskets have been changed,
As was seal on the throttle body.
Manifold was checked for leaks both before and after with non found!
Maybe need to check again.
 
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