Hello everyone, I’m having a spot of bother with my 2004 1.2 8v fiat panda dynamic. For the past 4 weeks I’ve been having problems with idling when the car is warm and warming up (from a quarter, to half way on the temp gauge). After 20 seconds or so whilst sitting in traffic the revs go up and down between 500 and 800 RPM.


Initially I plugged it into fiat ecu scan as soon as it started and didn’t find any error codes. Nevertheless, I did a self-adaption reset out of good measure and all was very well for about 2 weeks until the problem started again. I should also note I changed the spark plugs about a 1,000 miles ago (NGK ones) and put some new fiat HT leads.


Now I’ve just had it plugged into the computer again and there are no error codes, but my suspicion soon turned to the lambda sensors. It’s funny I should bring this up because 2 years ago (@40,000) I had the same problem and it lasted for about a month before the engine management light came on and it turned out there was no signal from the pre-cat sensor. So I replaced them both and haven’t really had any bother since until a month ago. Anyways I’ve just been testing the voltage readings for both the pre and post cat. With the engine running the pre cat oscillates between 0.1 and 0.8v just over every second or so but the post cat sensor constantly reads about 0.75v which I found odd.


I have a friend who also owns a panda 1.2 8v 2005 with 45k and I plugged in his car (as his idles perfectly) to test the voltages and I found something surprising. His pre cat does roughly the same oscillations as mine but his post cat almost always stays a 0 volts. This is something I can’t understand. Also his throttle position reads at idle 0.0 degrees while mine changes between 0.1 and 0.2 degrees.


I have only done 37,000 miles since the lambda sensors were last changed so they can’t be on their way out again surely. Also recently fuel consumption has increased by a fair amount, so I’m stumped as to what the problem is.

Is it the lambda sensors again, or the throttle body or something else I have missed? All suggestions welcome. Many thanks.

I doubt its the post-cat lambda, as the car will run fine without it in fact, and the MIL that comes on is typically to complain about the heater circuit not working.

Check all connections to the throttle body and then disconnect the battery for a couple of hours, as this will reset all the fuel and timing trims in the ECU. As it happens mine does the same, although its more likely to be an issue with my additional ECU to handle the mods than the same cause as yours. However, mine also clears for a few weeks if I reset the ECU via disconnect.

The idler valve working properly

Most Easterly Pandas said:

The idler valve working properly

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I did wonder if there could be a problem with the idle control valve, the last time I cleaned the throttle body was last August so is it worth cleaning it again and see what happens?

Inlet manifold leak? Might be worth searching for a leak with carb cleaner spray.