General Fiat 500 TwinAir (2015) goes into limp mode with P0236 on highway acceleration

[raketpontan]

Hi everyone,

I have a 2015 Fiat 500 TwinAir (manual transmission), and I'm struggling with an issue where the car goes into limp mode when I accelerate hard on the highway.
No engine light comes on but I get the fault code P0236 ("Turbocharger Boost Sensor A Range/Performance") as pending.

Here’s what I’ve done so far:

• Replaced engine oil
• Replaced spark plugs
• Replaced the MAP sensor
• Cleared the code multiple times

There are no visible vacuum or boost leaks in the engine bay. The car drives perfectly fine in city traffic (can accelerate hard af),
but the moment I put my foot down on the highway, it cuts power and goes into limp mode.

Has anyone else experienced this with the TwinAir engine or this fault code specifically? Any suggestions on what else to check?

Thanks in advance!

 

[GettinBetter]

Check the air filter, it'll cost you nothing to look at it's condition.

The only thing I can think of is the volume of air required to drive flat out ? any resistance in airflow would cause a partial vacuum and mess with expected readings?

 

[raketpontan]

Check the air filter, it'll cost you nothing to look at it's condition.

The only thing I can think of is the volume of air required to drive flat out ? any resistance in airflow would cause a partial vacuum and mess with expected readings?

I changed it about 18 months ago, but I’ve done around 25,000 km (15k miles) since then, so yeah, could be time again. I’ll check it — and if you wake up at night with any other ideas, let me know!

 

[GettinBetter]

... and if you wake up at night with any other ideas, let me know!

LOL. Ok, I will.

about 18 months ago

Mind you, that doesn't seem likely though, unless you've often been driving through an area with high particulate matter (dust, etc).

Ah, that reminds me, I once had a car which wouldn't rev high, it turned out to be the exhaust blocked. It reved high on initial start, but after a couple of mins wouldn't rise above idle. It looked pristene from the outside, but all the guts had corroded and gone down the end to block the exit. Once satisfied it was blocked I hammered a nail in the silencer and it was like a leaking compressor. New exhaust sorted it.

 

[puntodeltathema]

Worth checking the turbo wastegate vacuum actuator (under the heatshield at the front)- the hole in the clevis attaching the arm to the wastegate can go oval on the TwinAir leading to excessive play and a range of errors.