Hello again
Been a while but here goes.
I have just today had the engine light come.
The car has smelt fumey for a few days.
Is this a lambda sensor failed?
I replaced the bottom one this time last year and it cured the engine light when it came on.Dont seem to be drinking loads of fuel though this time like it did last time.

oh car is a 1.2 8v 2004 mk2b.
thanks
stu g

Check breather hose to air box underside has not popped off, this can give a stink

I'd read the codes, take it from there. Could be that it's running rich for a number of reasons.

why do people always blame lambda sensors?

When infact its a hole in X - or there shoe laces are untied...

Fault code read - see what the car thinks is wrong, base your diagnosis to see if car is correct

Ziggy

right i have the codes :-
P0300
p0300
p0420
after having the codes read driving it home the engine fault light went out.
its comes on as normal when you switch things back on and goes out when engine is started.
chap at the garage said the two lambdas seem to be ok according to the computer he had plugged into my car.

p0300 = Random Misfire detected
http://www.permoveo.ltd.uk/tabid/122/OBD-Error-Code/P0300/Diagnostics/Fiat/Default.aspx

p420 = Catalystic Converter below threshold
Ie its not converting gasses

http://www.permoveo.ltd.uk/tabid/122/OBD-Error-Code/P0420/Diagnostics/Fiat/Default.aspx

Run for abit - see if the light comes back on

Ziggy

cheers Ziggy.i will let you if things come back on.see how fuel goes aswell.it pasted it MOT only on friday too.

lilacmonkey said:

cheers Ziggy.i will let you if things come back on.see how fuel goes aswell.it pasted it MOT only on friday too.

Click to expand...

So the cat is doing its job then to pass the emissions test

I'd be connecting to the car with MES - and watching the 2 sensors values to see whats what

The PRE-cat sensor should peak and trough alot
The Post-cat should be adjusting but it should be a small waveform as it alters long term rich / lean status

Ziggy

the miss fire will put unburnt fuel in the exhaust which will cause the cat to not work properly fix the misfire save the cat.....

question for you guys in the know.does the ecu remember codes even if the engine fault light is not on.as the miss fire was a while ago when i had plug leads fail but the engine light came on and went off pretty much straight away.

forgot to say.i have driven from bristol down to cornwall last night a distance of 200 miles avg 60mph with an avg of 52mpg still over half a tank of fuel left.which is the same as every other time ive made this trip.and the engine light is still off thankfully.and the car is running sweet.

Yes the car will store Faults detected

So that if its intermitant, a mechanic can still see what the car thinks is wrong

Since the codes were cleared, and you've been trecking, i wouldnt worry till the car picks up on a fault again

Misfires are common due to HT's and coils breaking down with age and not been replaced

Ziggy

aaaghhhh after 500 miles of blissful driving the engine light comes on 5 miles from home.
I havnt got the codes yet but im guessing it will be miss fire.felt like a miss fire.
first up change plugs and leads?
then coil packs?
is there a way of getting packs tested?
thankfully they are not as exspensive as i first thought.
cheers in advance stu

There is a resistance check you can do on the low and high tension side

However without autodata with me I cant twll u what the figures are


Yes start with plugs and leads
Dont strip the plugs as they go in

Ziggy

Leads first, then plugs, then coil pack.

fingers99 said:

Leads first, then plugs, then coil pack.

Click to expand...

Yea i admit plugs rarly fail on the punto
The HT's do

OP if you take the plugs out, give them a good clean and regap them with new HT's see if that helps

If the misfire isn't cured, then replace plugs
Still missing - hit the coils with new

Ziggy