Technical P1555

Currently reading:
Technical P1555

The Beard

Prominent member
Joined
May 23, 2007
Messages
5,135
Points
839
Location
Manchester
In my slow but steady pursuit of a cure for the power loss that occurs under full throttle at around 3,500 to 4,000 revs, the latest Bosch diagnostic doofah tells me that the relevant fault code is P1555 and then waffles on about something to do with the brakes and probability.

The problem is, that searching on round 'tinternet this fault seems to come up mainly on Vauxhall sites, but is also mentioned on Ford and VW/Audi forums and also crops up on diesel and petrol engines.

Throttle Position Sensor crops up once or twice as do Turbo Pressure Sensors. So, er, any ideas?
 
Fiat manufacturer code P1555 = Brake/Accelerator Signal Implausible.

It just means that you've pressed the brake and accelerator pedals at the same time. The ECU never expects that to happen, so sees it as an inplausible situation and interprets it as a fault.

Sorry, it doesn't help with your power loss situation though.
 
Thanks Davren the message did use the abbreviation implau. and the word implausible. But seeing as I don't use left foot braking as a general routine, or, well ever actually I don't understand why that would come up as a fault.

I have seen it mentioned in connection with Vectra 1.8 & 2.2 litre as well as Focus ST and Audi A6/A6 1.9Tdi.

Bit stumped really because one forum even suggested (folowing on your theme) that possibly the switch on the brake pedal may need cleaning or adjusting because if the brake lights came on that may give the ECU the impression that there was indeed braking while accelerating.

So I'm still a bit stumped on this.
 
Get someone to follow you whilst attempting to make it happen. They can watch if your brake lights flicker.
 
In my slow but steady pursuit of a cure for the power loss that occurs under full throttle at around 3,500 to 4,000 revs, the latest Bosch diagnostic doofah tells me that the relevant fault code is P1555 and then waffles on about something to do with the brakes and probability.

The problem is, that searching on round 'tinternet this fault seems to come up mainly on Vauxhall sites, but is also mentioned on Ford and VW/Audi forums and also crops up on diesel and petrol engines.

Throttle Position Sensor crops up once or twice as do Turbo Pressure Sensors. So, er, any ideas?

Fault codes from P0001 to P0999 are generic and have the same meaning for all manufacturers. However, codes P1000 on are manufacturer specific and could have a different meaning for different manufacturers. P1555 will not mean the same thing for a Ford or VW/Audi as it does for a Fiat.

It's quite possible that a fault with the brake light switch could tell the ECU that you're braking when you're not, but I doubt that this alone, will be the cause of your problem.

The Stilo has an adjustable brake light switch that sometimes needs resetting (usually because the driver has put a foot under the pedal and lifted it). I don't know whether the Panda is similar.

There's a guide to resetting the Stilo switch on page 4 of this guide to replacing the switch:

https://www.fiatforum.com/stilo-gui...lems-changing-switch-gars4.html#content_start
.
 
Thanks chaps, I'll get Mrs. Beard to follow me. Be a little different from me folowing that woman with the huge breasts who lives round the corner. Mind you I think I might be getting pretty close to getting an ASBO or a High Court Injunction for that one so probably better off giving it a rest.

Once upon a time, the brake switch on my Chevette collected a lump of crud on it which resulted in the brake lights being on permanently so might be worth a punt.
 
Back
Top