My mom’s 500 Pop just developed a MIL/CEL. The car runs great, no leaks, no smells, no rough idle, no jerky shifts, and no loss in performance. We replaced the gas cap, and it’s still on. We are taking it O-Riley Auto Parts to get a free OBDII scan. What are the most common issues on a Fiat 500 (1.4 16v 100HP MultiAir N/A 4 CYL GAS w/ AISIN 6AT). It has about 45,400mi.

Note Fiat specific software is required a standard OBD2 scanner won't work, my first guess is Lambda sensor, but that's exactly that a guess have an expert with the correct software look at it?

John202020 said:

Note Fiat specific software is required a standard OBD2 scanner won't work, my first guess is Lambda sensor, but that's exactly that a guess have an expert with the correct software look at it?

Click to expand...

Are you saying that a regular obd2 scanner cannot tell me what’s wrong with our car? Are you in the US? If I’m right the US fiats can be diagnosed with any scanner.

I just looked up, any FIAT in the US can be diagnosed with ANY OBDII scan tool.

OBD2 Is a 'Standard'

Google or Wiki will give you the history

OnBoardDiagnostics was developed by VW in the US

Generation 2 started as a 'benchmark' for worldwide cars..

However only a small degree of the codes have agreed specific meanings.

Most cheap Chinese scanners..and a lot of expensive Trade ones default to VW mode (Bosch)

So a car running Marelli.. or Denso kit can give wrong definitions for a set code

Rocco Reviews said:

I just looked up, any FIAT in the US can be diagnosed with ANY OBDII scan tool.

Click to expand...

Code NUMBERS can be read.. correct

Diagnosed.. not always so

What are the most common problems that can trigger the CEL/MIL light.

Rocco Reviews said:

What are the most common problems that can trigger the CEL/MIL light.

Click to expand...

Unless someone has done a proper survey of cause of mil light triggering then no one knows.

Mil can be triggered by many many codes.
Guessing won't help.
Do what you are doing and get code read.
Then come back here and share.

I was of the understanding that obd2 codes were agreed to mean the same across the rang of manufacturers.

Obd2 codes do not cover all the functions available with manufacturer specific code readers but should tell you why mil on.

jackwhoo said:

Unless someone has done a proper survey of cause of mil light triggering then no one knows.



Mil can be triggered by many many codes.

Guessing won't help.

Do what you are doing and get code read.

Then come back here and share.



I was of the understanding that obd2 codes were agreed to mean the same across the rang of manufacturers.



Obd2 codes do not cover all the functions available with manufacturer specific code readers but should tell you why mil on.

Click to expand...

Yes, all of the codes mean the same thing across manufacturers.

jackwhoo said:

Unless someone has done a proper survey of cause of mil light triggering then no one knows.



Mil can be triggered by many many codes.

Guessing won't help.

Do what you are doing and get code read.

Then come back here and share.



I was of the understanding that obd2 codes were agreed to mean the same across the rang of manufacturers.



Obd2 codes do not cover all the functions available with manufacturer specific code readers but should tell you why mil on.

Click to expand...

We took the car to Autozone, for the past 24hrs the car was running on 3 cylinders. Cylinder 3 was misfiring, so we had the spark plugs replaced, and ignition coils 3 and 4 swapped at autozone. The car has never had a spark plug change in its life. The car is running better so I’ll update this post if the car turns from a MultiAir into a TriAir.[emoji23]

Rocco Reviews said:

Yes, all of the codes mean the same thing across manufacturers.

Click to expand...

Theres a huge list of manufacture specific code's that can mean massively different things from one brand to another

Basic codes are usually the same access brands such as misfires egr codes ect but still not allways guaranteed

Rocco Reviews said:

We took the car to Autozone, for the past 24hrs the car was running on 3 cylinders. Cylinder 3 was misfiring, so we had the spark plugs replaced, and ignition coils 3 and 4 swapped at autozone. The car has never had a spark plug change in its life. The car is running better so I’ll update this post if the car turns from a MultiAir into a TriAir.[emoji23]

Click to expand...

If a car is neglected and not serviced it will cost more money.
Driving with a misfire means fuel will enter the catalytic converter. Fuel in car will ignite when cat gets hot, causing cat to overheat. This overheating can rapidly destroy the cat which is a very expensive part.
So don't do it.

Rocco Reviews said:

The car has never had a spark plug change in its life.

Click to expand...

45k+ and never had the plugs changed? I really hope the originals were Iridium I dare not think what they looked like if standard and if so why weren't they replaced before?

John202020 said:

45k+ and never had the plugs changed? I really hope the originals were Iridium I dare not think what they looked like if standard and if so why weren't they replaced before?

Click to expand...

Probably like this beauty.

that gap is 2.5mm
Some people don't give a s*** about their cars, treat them like s*** then complain bitterly,saying that they "haven't done only thing wrong to it so why isn't it going right?"

jackwhoo said:

Probably like this beauty.

Click to expand...

Looks like a iridium plug but the tip looks damaged

John202020 said:

45k+ and never had the plugs changed? I really hope the originals were Iridium I dare not think what they looked like if standard and if so why weren't they replaced before?

Click to expand...

They were in surprisingly great shape. We had the ignition coil 3 put in coil 4's place so if it says that coil 4 is misfiring we just replace that coil. The replacement plugs that we bought are from Bosch. My dads Toyota Tacoma 4.0 V6 is almost at 160,000 miles on the original plugs. I wish every car was like that.

chris3234 said:

Looks like a iridium plug but the tip looks damaged

Click to expand...

It's a standard Bosch plug that is just way past it's service life

jackwhoo said:

If a car is neglected and not serviced it will cost more money.
Driving with a misfire means fuel will enter the catalytic converter. Fuel in car will ignite when cat gets hot, causing cat to overheat. This overheating can rapidly destroy the cat which is a very expensive part.
So don't do it.

Click to expand...

Apparently for the last 24 hrs the car was running on 3 cylinders and we weren't aware of it. My parents were about 45 mins from home when the light came on, and they said the car was running fine, and they were going up hills too. Yesterday evening I popped the hood to put the engine cover on, and the engine bay was so hot that the prop rod rubber that keeps the prop rod cool was hot to the touch, and temp gauge stayed level. This morning I warmed up the car and about 3 mins later when the car was warming up it ran rough for about 10 seconds and evened out. We never take our cars to the FIAT studio. They charge too much. It's been running great so far. I'll keep this posted.

Rocco Reviews said:

They were in surprisingly great shape. We had the ignition coil 3 put in coil 4's place so if it says that coil 4 is misfiring we just replace that coil. The replacement plugs that we bought are from Bosch. My dads Toyota Tacoma 4.0 V6 is almost at 160,000 miles on the original plugs. I wish every car was like that.

Click to expand...

Spark plugs come in all sorts of varieties and service life expectancy.

If they were in great shape why did new plugs cure misfire?
Did you measure the spark gap of the old plugs?
What plugs were fitted ? Make and part number?
What is service life of new plugs that were fitted?