Technical O2 Sensor Figures Low

[Seth110]

Help please for a newbie. I have bought my daughter her first car, a Fiat 500. Bought it private and a day after having it, the engine light came on. the car is a 1.2 8V POP 2015.

I have plugged it it and found a misfire of No2. Changed the plugs, leads and coil pack but it got worse - misfire on No2 and 3.

Seemed to happen when the car is under load. Did a compression test and all around 170 psi. Swapped 1 and 2 and 3 and 4 injectors round to see if that makes a difference, then only have a misfire on No2. Code was P0302. So I thought it may be the ECU causing the misfire so looked and found a loose earth lead on the ECU. Tightened that and took it for a test drive, no misfire but then got a O2 sensor fault {P0136).

Looked at the O2 sensor voltage and was getting about 0.7 on the downstream but only 0.01 to 0.15 on the upstream O2 sensor when was expected to get between 0.9 and 0.1V. Checked all the wiring, soing continuity checked between sensor plug and EXU and all good on both up and downstream sensors. Replaced the O2 sensor but still the same.

Have looked for air leaks but nothing. Fuel pump seems to be working fine. MAP is reading around 35 KPa at idle. The intake air temp seems a little higher than ambient. Ambient was 19 degrees today and it was reading 36 degrees on my software. I am going to check tomorrow when cold and see what its like. Apart from that, I am stuck.

Anyone got any suggestions?

 

[Seth110]

So, I checked the intake temperature when cold and was the same as ambient. Battery voltage is at 12.6V, no air leaks or leaks in the exhaust.

 

[The Panda Nut]

Ive found cleaning throttle body, MAP sensor and inside inlet manifild cured thison a similar miles Panda. Subsequently fitted catch cans on the crank case breather which cured t once and fo all.

 

[Seth110]

Ive found cleaning throttle body, MAP sensor and inside inlet manifild cured thison a similar miles Panda. Subsequently fitted catch cans on the crank case breather which cured t once and fo all.

Did you have similar issue with a low reading on the O2 sensor? Car seems to run ok around town.

 

[The Panda Nut]

Did you have similar issue with a low reading on the O2 sensor? Car seems to run ok around town.

Not sure ut misfire was repoted. GENERALLLY DROVE OK UNTIL ASKED to work then it started messing about. I found this a recurrent issue. I did have 02 issues once. Turned out the exhaust clamp had fallen off and it was leaking at the back box. MOT failed. Fixing exhaust restored the 02 readings. My 6hp Panda used more plugs than It should have but ran nicely if the TB was clean.