udderbrudder

I'd slow down on throwing parts at it. If you have an o2 sensor saying it's lean-then maybe it IS! I wouldn't condemn the sensor yet. If it's not switching-then maybe it's because the A/F mixture isn't changing. Or the signal wire or gnd to the sensor is bad. You can watch o2 voltages with a volt meter and introduce rich and lean conditions to see if it changes. Pinching off the fuel return line will create a rich condition and creating a major vacuum leak will create a lean condition. o2 sensor voltage ranges from approx. 100mv to 900mv. The fact that you have numerous o2 codes would make me even less suspicious of the sensors themselves.

Jbrew

None of that matters w/circuit malfunctions. Right, you don't throw parts at, - you look for the problem as I said earlier.

67kyle

I'm having the same problem on my truck, getting P0136 and p0156. Haven't been able to get rear o2s out. Is there any other circuit I need to check besides where the o2s plug in.

rangermark

I have climbed in it, over it, on it could not find any vacuum leaks, checked by way of plugging and unplugging, stethoscope, touching/feeling. I tried every way I could think
of.Did not find anything, so I moved on to looking for electrical harness problems, yeah no good there except the o2 sensor plug that runs down by emergency brake line was pinched between it and exhaust manifold. Could not tell if there was bad/bare wires because I was doing all this with engine HOT. Gonna do a reset and see what happens.
Well that did not work

udderbrudder

rangermark

This is really staring to hack me off, I am a FORD guy, and I like to work on them but, when it does not make any sense it frustrates me. I bought a 93 Bronco that would not idle previous owner installed TPS sensor upside down. I bought a 79 f150 and 78 bronco(my favorite years) rebuilt almost everything from ground up. My daughters own Explorer and Fiesta, my wife has 2011 Mustang, I have said all that to say this. Why can I not figure this out!!!!!!!!!!!!! I am sure it is a vacuum leak or plugged vacuum somewhere, it is kicking my.............. thanks for letting me rant.

Frank_Ford

Time to stand back and take a fresh look.

I strongly suspect that your P0136 and P0156 codes are kicking on because of a problem upstream from your OX sensors. i.e. problem with engine is kicking on the codes from reads by the oxy sensors.

Vacuum leak is one potential problem. Also, low fuel pressure (fuel filter or fuel pump), injectors plugged up or not working properly.

I would start by changing out your fuel filter (less than $10). and a bottle of fuel injector cleaner through your tank of gas. Less likely, change your air cleaner if dirty and clean your MAF valve. Also look for vacuum hoses that are bad like around the Pcv valve. Check for a leak in the intake manifold

Jbrew

Why are you doing all that? Something else wrong with it ? I'd fix those DTC's first, -they're meant to point in the right direction.

Jbrew

Sure is a strange one eh...-Both rears and they're spitting circuit dtc's.

Jbrew

Should be in the cross over IMO,- or the connectors. The connectors are sensitive. Just disconnecting and reconnecting have caused DTC's. They're finicky and need to be clean inside to work properly at times.