P0155 oxygen sensor

[terence mcgovern]

I just had to take my truck back from the local mechanic. He had been working on the pcm to clear many erroneous codes but had been stuck on the oxygen sensor. I’ve decided to try to troubleshoot it myself. Any good advice out there?

 

[DILLARD000]

TroubleCode p0155 = OxSensor21=LeftUpStream Heater MalFunc
Noting Year+Model+Engin+Trans+... in your Threads+Signature+Profile
will help+encourage answers to your questions.
Your profile notes "2010 4 Cyl XLT"; assuming this should be "2010 SportTracXLT with V6~4.0L~SOHC"?
Your have either 3 or 4 OxSensor probes, depending on exhaust arrangment; 2 upstream + 1 or 2 downstream.
2010 is over 12years old at this point; mileage?
Have OxSensors ever been changed; need to be renewed every 10years\100kMiles?
They wear out with age & mileage; need to be changed on same schedule as Plugs+Wires.
These are 4WireNarrowBand Bosch\Ford standard OxSensors; relatively easy to replace.
I suspect probe Heater wires have broken or have gotten too close to hot exhaust & melted.
A Bosch 15719 with 24i00 0m610 Long Cable+Plug is good to replace any Ford 4WireNarrowBand Sensor.
Click here for more info on OxSensors.

 

[terence mcgovern]

Yes, 2010 6cyl, 4.0 ohc xlt. Where are they located and is this something I can access myself?

 

[DILLARD000]

Yes, 2010 6cyl, 4.0 ohc xlt. Where are they located and is this something I can access myself?

My 2001 SportTrac V6~4.0L~SOHC is on the older\opposite end of the spectrum
from your 2010, so guessing on your Exhaust Manifolds+OxSensors+CatCons+Mufflers+...
Three OxSensors on my 2001 as shown below; yours could have a 4th OxSensor;
crawl underneath, locate & confirm; may need jackstands for clearance.
OxSensors easy to spot; cable-harness plugs can be a pain to reach+disconnect+reconnect.
Need 7/8"=22mm OffSet\Split HexSocket + Extensions + Ratchet.
Soak threads with PenetratingOil\LiquidWrench a couple of hours before trying.
If pipe bung is rusty, may need a MapGasTorch to heat up & loosen.
Route new cable away from hot exhaust + moving parts & secure with CableTies.
Click here for more info on OxSensors.

 

[terence mcgovern]

Thanks