Hi everyone, after several weeks and around £170 worth of petrol I still can not find out what is wrong with this punto. Its the 1.2 16v active sport one!

Let me tell you all of the problem I am facing! I just only hope some of you more experienced people could assist me with this dam thing.

So for the last few months my girlfriends punto has been terribly bad on petrol (like £170 a month bad). Our problems first began when her emissions light illuminated on the dash and she started to get a very violent missfire.

Doing the natural thing, I replaced her HT leads for some new ones and I also poped a set of new spark plugs in to help out, which solved the misfire problem!

Then I cleared the codes and sent her on her way. The next day we hit problems again (no misfires this time, thats gone now lol). Her emissions light illuminated again and she has a huge loss of power, car feels like it is in "limp" mode.

Now using a lot of fuel I presumed it would be her lambda sensor (her per car sensor looked like tat anyways) so I decided to change it. Purchased a £39 one direct from NPA with the plug already installed. Fitted it no problem and cleared her code. BUT still the same problem.......

So I read her codes and I was presented with this...

U1602 - CAN bus communication, interior faulty

P0340 - Camshaft position sensor component defective

P0130 - 02 Sensor (bank 1, sensor 1) component defective

P1135 - 02 Sensor heater resistance (bank 1, sensor 1) incorrect value


Now reading the above I am guessing the cheap ****ty lambda sensor needs replacing (only the pre-cat, if someone could confirm this)?

now I believe my main problem lies with the P0340 - Camshaft position sensor component defective error. I have replaced the camshaft sensor for one of ebay, cleared her codes and try again, only to get the same report. Anyone have any ideas AT ALL on this?

Can someone also tell me what the U1602 - CAN bus communication, interior faulty error is? I have no idea what this is, nor have I heard of it! I appreciate any replies! Thanks

CANBUS is the communications protocol that the ECU uses to communicate with the various sensors dotted around. I'd say that would be the main issue, and in my opinion is caused either by faulty wiring or (less likely) a faulty ECU.

put the old sensor back in, swap it with the post cat one to see if it helps.

There have been reported problems with universal types ones

Clear the u1602 code and ignore it unless it keeps cropping up

The camshaft sensor
P0340 makes its Cam Shaft A circuit
So it could be anything from the sensor, to wiring to the ECU
Get checking the wiring for high resistance, corroded connectors, wet connectors, snapped cables, frey'd cables etc etc
Check the sensor is the correct type, and its producing the correct voltages (osilioscope is needed here)

the 2 lambda sensors are
generic or not fiat specific, but both relate to the lambda as said
If it was recently replaced, they may have not cleared the codes

Tbh - i'd be tempted to clear the codes and run for a week and rescan to see whats going on

Ziggy

Get a o2 sensor from a reputable parts supplier or a oem one

Ebay car parts can be a gamble usually an expensive one.

If you can get them off a Punto in scrapyard (if there not corroded in or seized solid and not without destroying the threads)

Then do a swap in a scrap yard and see if the sensor is a good one or not

2nd hand parts you do play a HUGE risk tho

Ziggy

Thanks for all your helpful replies everyone! Just an update:

I have seen far to many threads about this issue and I have not come across one yet that has a solution or seen anyone post after their problem was fixed!

I would like to inform everyone that this problem is now fixed, it turned out that the timing had skipped and was out by a mile, very lucky that she didn't bend valves! Apparently although her timing belt felt reasonably tight, and that it was not skipping teeth, it had slipped due to not being tensioned?!?! (even though it felt like it was, i give it a good tug). This was literally confusing every possible sensor on her car lol! So to anyone who has the above problems ^ get your timing checked. We ended up fitting a new timing belt, tensioner and waterpump Thanks everyone!

The phase sensor was probably picking up on the fact the pistons were pushing the valves shut, and as you said
Lucky you aint smashed the valves into the pistons

Ziggy