Technical Multiple fault codes on Fiat 500 – Some new after tire replacement, seeking advice

[Vinnyfiat]

Hi everyone,

I’m new here, so hello! I recently joined this forum to get some advice about my Fiat 500, and I hope to learn from the experiences of others.

I own a Fiat 500 and recently had the tires replaced with 195/45 R16 ones. Shortly after the replacement, I noticed that the ESP light sometimes turns on while taking corners. To investigate further, I scanned the car with an OBDLink MX+ using the Car Scanner app and found several fault codes. It’s worth mentioning that some of these codes were already present before the tire replacement:


• P0700: Transmission control system, MIL request - circuit malfunction


• P1760: Pressure Control Solenoid -A- Short Circuit


• P0857: Traction control input signal - range/performance problem


• P0856: Traction control input signal - malfunction


• P0504: Brake pedal position (BPP) switch A/B - correlation


• B1010: BCM (Body Control Module) - Archive (inactive)



Symptoms:


• The ESP light sometimes turns on during corners but doesn’t stay on. Even though we drive normal


• Otherwise, there are no obvious driving issues.



Actions taken so far:


• Checked the tire pressure and adjusted it to the recommended level.


• Cleared the fault codes; however, they returned after a short drive.


We suspect that the recent tire change might have affected certain systems, such as the steering angle sensor or ESP, which could explain the new issue with the ESP light. However, the transmission-related codes and other pre-existing issues likely need separate investigation.


Question:


As I’m new to troubleshooting fault codes like this, I was wondering if anyone has experienced similar issues. What would you recommend as the best steps to resolve both the new and pre-existing problems? Any advice or guidance would be greatly appreciated! Please note that the garages here are so busy that I can’t get an appointment anytime soon so try to do it myself.





Thank you for your help in advance, and I look forward to being part of the community.

 

[the green vanper]

Hello,

Globally FIATs don't like generic scanners and apps.

There's a dedicated FIAT app, MultiEcuScan.

I'm not saying that the OBDLink MX+ and CarScanner are not correct, but might be.

What was the size of the original tires? Have you installed the new ones on the original rims?

 

[steveras57]

Hi Is there anyone near you with MES software that could try doing a steering re-learn for you? -Its likely that the changes you have done are now outside the systems stored parameters and it needs a re-set so the computer knows what values to expect!.

 

[A3jeroen]

Do you have the same size on all 4 wheels?
If ABS sensors sense a (too) big difference in speed it will throw tantrums like this.

gr J

 

[Vinnyfiat]

Hello,

Globally FIATs don't like generic scanners and apps.

There's a dedicated FIAT app, MultiEcuScan.

I'm not saying that the OBDLink MX+ and CarScanner are not correct, but might be.

What was the size of the original tires? Have you installed the new ones on the original rims?

“Thank you for your reply! Yes, the tires are mounted on the original rims. I am not sure about the size of the original tires, the new once’s are 195/45 R16 Based on your suggestion, I downloaded MultiECUScan (MES) and performed another scan. During the brake session, a new code came up: C1215-29 - Brake pedal switch - Signal invalid.


To address this, I attempted some recalibration steps, including:


• Resetting the lateral and longitudinal acceleration sensors


• Steering angle calibration


However, both attempts resulted in an error: ‘Failed to execute’ (either ‘Request out of range error’ or ‘Status: 7F’). I did buy the whole version of the software do that’s not it.


Additionally, when connecting to the brake session in MES, the car’s board computer displayed messages stating that EBD is broken, with ESP, ABS, and Hill Holder not available. I cleared the fault codes, and while they reappeared once, they have not returned so far.


Do you have any recommendations on what might cause these errors or how I should proceed from here?”

Let me know if you want any further refinements!

 

[Vinnyfiat]

Hi Is there anyone near you with MES software that could try doing a steering re-learn for you? -Its likely that the changes you have done are now outside the systems stored parameters and it needs a re-set so the computer knows what values to expect!.

I downloaded it and did the test again, I will add the outcome to the original post. Thank you!

 

[Vinnyfiat]

Do you have the same size on all 4 wheels?
If ABS sensors sense a (too) big difference in speed it will throw tantrums like this.

gr J

Thanks for your response! All four tires are the same size (195/45 R16), and I’ve checked the ABS sensor speeds—they appear consistent. Do you have any idea what else could cause the ‘Vehicle Speed Incoherence’ error code?”

 

[A3jeroen]

Compare them to the original size. If out too much the ABS computer can' t cope.
I know it's the right size for an Abarth, but not sure about a normal 500.

gr J

 

[Vinnyfiat]

Hi everyone,

I’m new here, so hello! I recently joined this forum to get some advice about my Fiat 500, and I hope to learn from the experiences of others.

I own a Fiat 500 and recently had the tires replaced with 195/45 R16 ones. Shortly after the replacement, I noticed that the ESP light sometimes turns on while taking corners. To investigate further, I scanned the car with an OBDLink MX+ using the Car Scanner app and found several fault codes. It’s worth mentioning that some of these codes were already present before the tire replacement:


• P0700: Transmission control system, MIL request - circuit malfunction


• P1760: Pressure Control Solenoid -A- Short Circuit


• P0857: Traction control input signal - range/performance problem


• P0856: Traction control input signal - malfunction


• P0504: Brake pedal position (BPP) switch A/B - correlation


• B1010: BCM (Body Control Module) - Archive (inactive)



Symptoms:


• The ESP light sometimes turns on during corners but doesn’t stay on. Even though we drive normal


• Otherwise, there are no obvious driving issues.



Actions taken so far:


• Checked the tire pressure and adjusted it to the recommended level.


• Cleared the fault codes; however, they returned after a short drive.


We suspect that the recent tire change might have affected certain systems, such as the steering angle sensor or ESP, which could explain the new issue with the ESP light. However, the transmission-related codes and other pre-existing issues likely need separate investigation.


Question:


As I’m new to troubleshooting fault codes like this, I was wondering if anyone has experienced similar issues. What would you recommend as the best steps to resolve both the new and pre-existing problems? Any advice or guidance would be greatly appreciated! Please note that the garages here are so busy that I can’t get an appointment anytime soon so try to do it myself.





Thank you for your help in advance, and I look forward to being part of the community.

Hi again, everyone,


Thanks to your helpful suggestions, I’ve taken the following steps and found some new results:


1. Tire Confirmation:


I confirmed that the new tires are the correct size (195/45 R16) and mounted on the original rims.


2. Using MultiECUScan (MES):


Based on recommendations, I downloaded the MES software and rescanned the car. Here’s what I found:


• In the brakes section, I got a new fault code: C1215-29 - Brake pedal switch - signal invalid.


3. Calibration Attempts:


I attempted recalibration for:


• Steering angle sensor.


• Lateral and longitudinal acceleration sensor reset.


Unfortunately, both attempts failed, returning errors like:


• “Failed to execute (Request out of range error).”


• “Status: 7F.”


4. Dashboard Messages:


When connecting to the brake module, the dashboard displayed:


• EBD broken


• ESP, ABS, and hill holder unavailable.


After clearing the codes, they briefly reappeared once, but not again so far.


Next Steps / Questions:


• Does anyone have insights into resolving the failed calibration errors (Status: 7F and Request out of range)?


• Could the brake pedal switch error or the tire change still affect the ESP system, even though the codes haven’t returned?



Thanks again for all the help so far! Looking forward to hearing more advice from the community.

 

[Zardo]

ESP, ABS, and hill holder unavailable.

A faulty brake pedal switch will trigger these.

When the brake pedal switch gets faulty, there might first be an intermittent fault, like appearing and disappearing for months. It was like this in my case (on a Punto Evo). When it fails, it triggers the above and you'll also lose cruise control. Of course, other reasons might exist which also would trigger the same faults, like a faulty wheel speed sensor.

A simple test for the brake switch: with ignition on, clear the fault codes. Using an OBD command, switch on the brake lights (without anybody touching the brake pedal). It should be available with the tests. All three lights should light up by remote control. Stop the brake light test. Now you know all your brake lights are actually functional (like the light bulbs or LEDs).

Next, with ignition on, ask somebody to step on the brake pedal or film your car's rear with your phone. The brake lights should light up. If they don't, the brake light switch is faulty.

If they do light up, the brake light switch might still be faulty, but it's likely an intermittent fault.

Typically, a faulty brake light switch, with the error cleared by OBD, either will trigger immediately the same error again upon ignition on (whether you've stepped on the brake pedal or not), or, if it does not reappear immediately and you're able to start driving without stepping on the brake pedal first, once you step on it the error messages might reappear at the same moment (ESP, ABS and hill holder unavailable). So in the later case you understand that they're related to your stepping on the pedal.

Anyway, I'd recommend doing those tests and if still in doubt or the error is confirmed, replace the brake pedal switch. It's already highly likely with the OBD fault code.

This may not solve your other problems, I believe your car has multiple issues.

Also check for a wire fault (like some critter having had a go at your cables) or water ingress in the electronics.

 

[Vinnyfiat]

A faulty brake pedal switch will trigger these.

When the brake pedal switch gets faulty, there might first be an intermittent fault, like appearing and disappearing for months. It was like this in my case (on a Punto Evo). When it fails, it triggers the above and you'll also lose cruise control. Of course, other reasons might exist which also would trigger the same faults, like a faulty wheel speed sensor.

A simple test for the brake switch: with ignition on, clear the fault codes. Using an OBD command, switch on the brake lights (without anybody touching the brake pedal). It should be available with the tests. All three lights should light up by remote control. Stop the brake light test. Now you know all your brake lights are actually functional (like the light bulbs or LEDs).

Next, with ignition on, ask somebody to step on the brake pedal or film your car's rear with your phone. The brake lights should light up. If they don't, the brake light switch is faulty.

If they do light up, the brake light switch might still be faulty, but it's likely an intermittent fault.

Typically, a faulty brake light switch, with the error cleared by OBD, either will trigger immediately the same error again upon ignition on (whether you've stepped on the brake pedal or not), or, if it does not reappear immediately and you're able to start driving without stepping on the brake pedal first, once you step on it the error messages might reappear at the same moment (ESP, ABS and hill holder unavailable). So in the later case you understand that they're related to your stepping on the pedal.

Anyway, I'd recommend doing those tests and if still in doubt or the error is confirmed, replace the brake pedal switch. It's already highly likely with the OBD fault code.

This may not solve your other problems, I believe your car has multiple issues.

Also check for a wire fault (like some critter having had a go at your cables) or water ingress in the electronics.

Thank you for your response, Henk. I’ve checked both the MES software and the other OBD software I have, but there doesn’t seem to be a specific function available to test the brake lights directly. However, I did test the brake lights manually by pressing the brake pedal, and they are working properly.

I haven’t had the chance to inspect the cables yet since I’m not entirely sure where to look, and it’s quite dark outside right now. Do you have any specific tips or guidance on what to check and where to start with the wiring? Thanks again for your help so far, it’s much appreciated!

 

[Zardo]

Thank you for your response, Henk. I’ve checked both the MES software and the other OBD software I have, but there doesn’t seem to be a specific function available to test the brake lights directly. However, I did test the brake lights manually by pressing the brake pedal, and they are working properly.

I haven’t had the chance to inspect the cables yet since I’m not entirely sure where to look, and it’s quite dark outside right now. Do you have any specific tips or guidance on what to check and where to start with the wiring? Thanks again for your help so far, it’s much appreciated!

Haha, yes simply using the foot stepping on the pedal works, too (if they light up) - if they don't, you don't know if it's the lights or the switch. I use AlfaOBD and the brake light tests is one of the available tests (I think it was via the body computer ECU). Kind of cool to remotely trigger the brake lights using a bluetooth OBD dongle.

Cables: the brake light switch cable crosses over from the brake light switch in the foot well to the engine bay. So I presume it's rather unlikely to have rodents in the passenger cabin, but some people actually keep rats as pets ;-) Otherwise, check the cable harness which connects to the ECU and (for other causes) the cable of the wheel speed sensor in the wheel arch. I actually had both at the same time: a wheel speed sensor cable partially eaten by the tyre and an intermittently faulty brake light switch, the combination of the two faults gave me quite some headaches.

 

[the green vanper]

In the body computer:

And the Actuators tab:

 

[A3jeroen]

Brake switch has 2 separate circuits. One for the lights, one for the bodycomputer => ABS computer. For the cost of it I'd install a new one. Make sure to calibrate it. Lift the pedal, pull out the pin on the switch and let the pedal slowly return to the normal position (pushing in the pin to the right length).

gr J