Hello Stilo people

Just bought myself a cheap little 3 door Stilo with issues!

The car has been cared for and wanted for nothing. It only reads 83k has leather seats, 17" alloys, new clutch a year ago, used engine with 66k 6 months ago (after cambelt failure), full history, 11 months MOT etc etc - basically I think it needs saving!

Apparently it stopped working 2 weeks ago. Basically dash reads engine fault. Engine starts but sounds lumpy and the throttle does not work at all! The previous owner took it to his mechanic (who fitted the engine) he looked at the codes and assumed it was throttle body, so took that out and cleaned it thoroughly - no change. He kept fault finding but found nothing, the bill got too high so the owner sold it to me. The mechanic is not a Fiat specialist and just said - "I don't think it's the ECU as it was tested ok 6 months ago - maybe it's just a car that doesn't want to be fixed!"

Hoping someone might be able to advise a direction to point me in.

Originally codes read:

P0141 -O2 sensor (12)
P1687 - Electrically actuated throttle (learn stop)
P1220
P0136 - O2 sensor (7)
P1684
P0460 - Fuel level sensor (1)
U1600 - Immobilizer: key faulty.

I cleared all the codes and started the engine and only two keep coming back (although I couldn't say if driving the car may bring back others!)

P1687 - Electrically actuated throttle (learn stop)
P1220

Any ideas from you knowledgable lot??

Thanks in advance

tell us the engine!!!
did you try to do a "self-adaptation reset"?
if you have the 1.6 you need to do the "phonic wheel learn"

Sorry! Apologies - yeah 1.6.

I haven't done any kind of resets? And have no idea what a phonic wheel learn is, as am not to great with Fiats :/- but would be happy to try anything?

Managed to find some information on here (apologies, should have looked harder before posting) Indications point to throttle body, the ecu or wiring inbetween. Someone also mentioned the peddle sensor - is this likely with these fault codes, or is the former area the place to begin.

Thanks

do you have a elm327 interface? You will need it if you want to keep the Stilo (or other fiats)
get one from ebay..it's like 10€. Then you need the Multiecuscan software.

This is how you can get a more detailed description of the errors and different parameters.
You can use that to also see different parameters.. and plot graphs..like plot the movement of the throttle body.

Before anything use a multimeter to check that the throttle body recieves 5v from the ECU.. and also check the continuity of the wires between the throttle body and the ECU.

Hi thanks for the response.

Can't find wiring break. Throttle body has been swapped - no change.

Think I may be looking at ECU.

Quick question for those out there who know!

My ECU code is IAW 5NF.T9

I have seen a 1.6 16V stilo ECU code IAW 5NF.T1 at my breakers (I know someone who can virginise it).

Is this compatible or do i strictly need IAW 5NF.T9??

P0141 O2 Sensor Heater Circuit Malfunction (Bank 1 Sensor 2)
P0136 O2 Sensor Circuit Malfunction (Bank 1 Sensor 2)

Click to expand...

these 2 will come back. faults for your Post cat Lambda sensor. i just bought an NTK replacement part number is OZA659-EE31 should be between £70-100. you can get cheaper... but probably false economy. The last one i bought was about £35 and its failed within 20,000 miles Lambdas should be good for 5 times that.

P1220 Throttle position (signal implausible)
P1684 Motorised throttle (plausibility)

Click to expand...

plausability errors are a bit of a weird one, could be a whole bunch of stuff causing it, first thing is first, try the 'relearn' (link is in my sig) and see if the faults become inactive. Secondly, i dont believe they put the MIL on... are you experienceing any drivability issues?

P1220 Throttle position (signal implausible)
P1684 Motorised throttle (plausibility)

These signal that there is a problem with the ground or with the +5v to the sensor.
I think you can see the voltage with MES.

Do not go any further. check and double check.
also wires...using a multimeter in ohm mode is not enough.. test the wires with a load on them... like a small 12v 5w bulb, make sure the wires can carry the load.

Another possibility is that someone who worked on the car before you stuck something inside the throttle connectors on the harness side..and they are no longer in good contact with the throttle.

One other important thing!!!!!
You also have problems with the O2 sensors.. make sure that some wire is not making contact with a hot/vibrating piece of metal.... it can damage the isolation on the wires, grounding the wires from the ECU and causing all sorts of unrelated problems.

You really have to go wire by wire from the ECU to the different sensors; testing them with a small load on them always checking you are not touching wires together; preferably do as much of the tests with the battery disconnected to avoid damaging the ECU. You can never be to careful!

Appreciate the info guys.

The reason I was thinking ECU is because of all the random faults - I'm just going on the experience with Alfa's I've had in the past. I can get a virginised one for £100 - £120 delivered and worst case scenario, if it doesn't cure the issues I can throw it back on Ebay and get most of that back even though it will need virginising again - they seem to be like hot cakes...!

If there is a real issue with the O2 sensor I'll deal with that after I get the car running - and in answer to your question 'does the car run ok' Richy. Nope. Throttle does nothing. Car does idle but defo seems a bit lumpy. I tried the relearn procedure but had no joy at all.

The idea of testing all the wires is what I was afraid of. It's a maze of wires in there and I'm certainly no autoelectrician (wiring a domestic plug sums up my skills!)

I do have the free version of MES and the correct adaptor, I'll have a look if I can learn anything tomorrow.

If the ECU doesn't help I may have to get in someone to do the wire check, or maybe do it the other way round! :/

I don't think it's the ECU... at leash not based on those errors, they don't seem random faults.
The faults might be linked together! one fault can cause the other.
Do not treat them as separate problems.
When the ECU goes on Stilos they usually throw a "loose connection error" or something like "processing unit fault".

You don't have to test all the ECU wires... there are like 4-5 wires for each O2.. so 8-10 wires+ 5-6 wires for the throttle ... it would take like 1-1.5 hours all in to properly test those wires.

If you're not confident take it to a auto electrician.

1.6 ECUs are known to go down but not for these faults. i'd advise doing a few checks before blowing money on an ECU

heres my quick Snippet of the wiring diagram from ECU(M10) to throttle body



and heres the ECU Pinouts locations,


theres a discrepency in the info i have where the wiring diagram denotes Pin 43 at the ECU... BUT... the 'pinout' locations i have denotes Pin 42 (pinout shows pin 43 as 'not used') so it could be either Pin 42/43 that's connected to Pin 4 at the throttle body.

you need to look at all the continuities between

• ECU Plug A Pin 2 > Pin 2 Throttle Body
• ECU Plug A Pin 3 > Pin 1 Throttle Body
• ECU Plug A Pin 15 > Pin 5 Throttle Body
• ECU Plug A Pin 40 > Pin 6 Throttle Body
• ECU Plug A Pin 42/43 > Pin 4 Throttle Body
• ECU Plug A Pin 46 > Pin 3 Throttle Body

the ECU pinouts are as follows
Pin 2 = Acc Pedal Sensor Supply (Track 1) {5v}
Pin 3 = Acc Pedal Sensor Supply (Track 2) {5v}
Pin 15 = Acc Pedal Sensor Ground (Track 2)
Pin 40 = Accelerator pedal potentiometer signal (Track 2)
Pin 42/43 = Accelerator pedal potentiometer signal (Track 1)
Pin 46 = Acc Pedal Sensor Ground (Track 1)

If your continuity checks come back ok... Check for 5v signal between Pins 2 & 5 and Pins 1 & 3.
Between Pins 6 & 5 and Pins 4 &3 you should see anything below 5v, varying with throttle input

Something else to bear in mind here is that the wiring runs through the D4 connector, which is notorious for causing issues. It is located under the battery tray and is a black (iirc) rectangular connector that is approximately 30mmx60mm. My first port of call would be to disconnect and check this plug for any signs of, even slight, water/dirt ingress. Maybe spray with some electrical cleaner and reconnect. Recheck fault status before carrying out wiring checks.

As a last resort you can unscrew the plastic cap from the throttle body and you will see the 'copper tracks'. You can carefully clean them with a cotton bud and methylated spirits/contact cleaner and regrease with vaseline. This has been known to work but isnt a common fix.

Thanks guys. Really helpful from both.

Quick question! Just taken off the battery to give it a boost and found this unconnected effort??

Thoughts?

thats the D4b for Cruise Control... you're 'semi-predisposed'

D4a connector is identical shape but diferent colour with a plug connected.