Technical P0135 and P0141 Fiat Panda

[Fiat2020]

I read two trouble codes P0135 and P0141 with my fiat panda 1.1 fire from 2004. I cleared the trouble codes again and it came back after 500 meters. I measured the resistance of both probes and it was good. The F11 fuse is also intact and the probes receive the same voltage as the battery.
I read my running engine with an elm237 and the app torque lite during a drive of 14 miles. At the end of this ride, the first sensor had reached a maximum value of 0.5 volts. Sensor 2 has a maximum value of 0.3 volts. Are both sensors broken after all, because the faults are coming back?

 

[DaveMcT]

The 1.1 Panda is noted for wiring problems at the engine ECU connector or in the bundle leading to the connector. It can cause coil faults and O2 sensor faults.

A forum search found this. There are many more.
https://www.fiatforum.com/panda/461290-1-1-misfire-loss-power.html?461290=#post4348330

 

[koalar]

Worth checking for damaged cables

run your fingers along the cables.

look for melting rubbing.

 

[koalar]

F11 ?


Are you sure thats right. Doesn't look right for my car. "Secondary services" although there are different wiring from year to year


and my steering is on the other side

 

[koalar]

have you had the exhaust fixed recently ?

 

[Fiat2020]

The error codes came after I sprayed my engine block with water in a car wash box

 

[koalar]

ahh that changes things.

connectors are attach to the front right of the engine and in direct line of any engine cleaning.

check the connectors. Physically disconnect and check. also check the wiring loom around here for chaffing. Getting dislodged and melted.

 

[Fiat2020]

I checked the cables and found no problems. So I experimented a bit. I replaced both lambda probes with copies of the scrapping. The first sensor runs from 0.1 to 0.9 volts when the engine is warm. I think this is sufficient. The second sensor rises to 0.4 volts at 100 miles per hour. I understand that the second lambda probe must have a continuous signal of 06 - 0.8 volts. I do not think this is sufficient. The error codes p0135 and p0141 return. Could it be that the second sensor is not functioning properly and both codes come back as error codes?

 

[koalar]

the error code is the heater circuit. Thats the two wires on the sensor lead that are the same colour. When you First start the car if you back probe one side should be around 14 volts there will be a small voltage drop and measure slightly less. Thats with one end of the multi meter on ground. Once the car is up to temperature I suspect the heater will be switched off

As far as I know there now way to check with a scanner

You can take the sensor out and feel if its getting hot. But only when the engine is cold and running.

 

[MrMagoo]

Download a copy of elearn and trace back and confirm to the ECU pins. I would also clean and remake every visible under bonnet earth connection. I use a smear of copper grease on the joints.

 

[DaveMcT]

Swap the O2 sensors over and see what happens to the codes and voltage values. Stay the same it's a wiring issue. Fault moves its a sensor issue.

 

[koalar]

Download a copy of elearn and trace back and confirm to the ECU pins. I would also clean and remake every visible under bonnet earth connection. I use a smear of copper grease on the joints.

ECU is only on the ground side of the heater element and is used to detect a problem in the circuit.

You still need to check the voltage to the element by back probing the connector

 

[koalar]

on the sensor the two cables the same colour White on my car should measure 12-14 volt from an earth point. Cold engine and running.


and if you disconnect the cable the two bottom pins should read 3 ohm, if this is correct you can almost guarantee the element is okay and its a ground or power problem.


my meter reads .3 ohms just for the leads

 

[Fiat2020]

Thanks for the tips. I measured both lambda sensor before I placed them and that was around 3 ohms. I measured the voltage in the connection of both probes. The white wire is the plus and the gray wire is the mass (minus). Here I measure 13.9 volts. If I connect the minus of my multimeter directly to my battery, I measure 14.1 volts. If it is a ground or power problem. What tips do you have to solve it.

 

[MrMagoo]

Not sure if the lambda sensor heating circuits are independently monitored. You said the fault occured after visiting a carwash but that may have been a coincidence or could have been a trigger. As DaveMcT stated, have you swapped over the lambda sensors?

 

[koalar]

if both white wires measure around battery voltage. The fuses, elements and wiring to the O2 sensors are all okay

Are you sure there connected the right way round ? Its easy to reverse as the connectors are identical.


I believe Its one of the few codes that won't self clear and needs clearing with a scan tool.