2001 wrong exhaust and o2 sensor problem | Ford Explorer Forums - Serious Explorations

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2001 wrong exhaust and o2 sensor problem


November 22, 2012
Reaction score
City, State
Vancouver, BC
Year, Model & Trim Level
2001 Explorer xlt V6

I have a 2001 xlt with sohc. It had a lack of power and an idle reving problem. The code i got was P0135 so i replaced the upstream 02 sensor on the passenger side and the only down stream sensor. Also cleaned the MAF. This fixed the power problem but it still misses while at idle. From what i understand my truck should have 4 o2 sensors and only 3 cats but i have 4 cats and 3 o2 sensors (two upstream and one down stream)

PROBLEM: I'm getting a code error P0136 bank 1 sensor 2 see p2270, p2271
(the engine light is not on)

what do i do.

here is a video of the current idle, the missing is minor but fuel cost is way up.


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Those codes make you want to run out and change sensors, but that don't always fix the issues.
I can't see your video because it is private, but these trucks have bad intake gaskets which could give you O2 sensor codes and crappy idle.

Without a scanner with datastreams it is difficult to tell. I would like to know what the fuel trims are for example.

The codes you posted could be because of faulty wiring as well, check for any melted wiring harnesses.

O2 sensor configuration

P0136 02 Sensor Circuit Malfunction (Bank I Sensor 2)
P2270 - O2 Sensor Signal Biased/Stuck Lean Bank 1 Sensor 2
P2271 - O2 Sensor Signal Biased/Stuck Rich Bank 1 Sensor 2

If your PCM was expecting four O2 sensors instead of the three installed the PCM would set DTCs associated with the heater circuit for the missing sensor. My 2000 Sport has four O2 sensors: one on each downpipe prior to each cat and one on each output of the two cats prior to the muffler input.

I suspect that your XLT O2 sensor configuration is similar to the 2001 Sport Trac's. I suggest disconnecting the downstream O2 sensor to see which O2 sensor heater fault is set by the PCM to make sure they are connected correctly.

I don't think you have the "wrong" exhaust, like it was said it would trigger other codes too. Probably the SOHC came with two different configurations and PCM programs for each configuration. Input your VIN here to search for exhaust parts that are appropriate for your VIN.
Is your exhaust like the one below:

Or like this one:

Sadly My code reader does not do data stream.
sorry about the video fixed that.
Thanks for the link for ford parts the second picture (single inlet muffler) is what i have.
I did think i saw a small bit of corrosion on the end of one of the pins when i changed the down stream sensor. I blew out the female end on the truck with compressed air. Is there any fluid that i can safely add to make sure the connection is good? The wiring appears to be intact from what i can see.

Update: I tried wd40 in the connecter which reduced the problem but it was still there. Last week I was able to use a hoist and standing under the car allowed me to get a better look and it appears there is a small section of melted wiring not far from the down stream sensor. I have not fixed this problem yet but i have found the source of my issue. Thanks again for the advice

hi good night everyone im charles good to meet you .