Have you ever seen a downstream o2 look like this?
Thread Starter
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Senior Member
Joined: Jul 2006
Posts: 256
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From: Salt Lake City, Utah
Have you ever seen a downstream o2 look like this?
I was getting
P0138 O2 Circuit High Voltage (Bank 1, Sensor 2)
P0054 HO2S Heater Resistance (Bank 1, Sensor 2)
P2271 O2 Sensor Signal Stuck Rich (Bank 1, Sensor 2)
I replaced all the o2's for good measure.
Both fronts and the driver's side downstream looked fine (but had a tiny amount of white caked fouling, but not much at all).....but the passenger side downstream.......
The driver's side taps into the exhaust pipe from the top, at a 45*and is about a foot after that bank's cat. The passenger side taps into the pipe directly from the side at the 3 o'clock position and is directly behind that bank's cat about 3". I have magnaflow hi-flow cats. Both of the front o2's looked totally normal.
I have been keeping an eye on my coolant and oil levels, and everything is and has been kosher for months. I have used in-tank fuel injection system cleaners before, could that do this?
If the cats were bad, after changing all the o2's and clearing the CEL's, wouldn't it throw catalyst codes?
P0138 O2 Circuit High Voltage (Bank 1, Sensor 2)
P0054 HO2S Heater Resistance (Bank 1, Sensor 2)
P2271 O2 Sensor Signal Stuck Rich (Bank 1, Sensor 2)
I replaced all the o2's for good measure.
Both fronts and the driver's side downstream looked fine (but had a tiny amount of white caked fouling, but not much at all).....but the passenger side downstream.......
The driver's side taps into the exhaust pipe from the top, at a 45*and is about a foot after that bank's cat. The passenger side taps into the pipe directly from the side at the 3 o'clock position and is directly behind that bank's cat about 3". I have magnaflow hi-flow cats. Both of the front o2's looked totally normal.
I have been keeping an eye on my coolant and oil levels, and everything is and has been kosher for months. I have used in-tank fuel injection system cleaners before, could that do this?
If the cats were bad, after changing all the o2's and clearing the CEL's, wouldn't it throw catalyst codes?
Thread Starter
|
Senior Member
Joined: Jul 2006
Posts: 256
Likes: 0
From: Salt Lake City, Utah
I got this response from a non-F150 forum I frequent, that attracts lots of tuners familiar with modified Fords
Originally Posted by gmorrell
OBD2 monitors the heater current to the sensors, if it threw a P0054 HO2S Heater Resistance code, then that sensor may have an open heater, if so, it wasn't operating at proper temp and might have fouled. Downstream, post-cat O2's don't get the exhaust heat benefit of the upstream sensors, so they need more and constant heater current to stay at operating temp and be self-cleaning. This could also be a blown O2 sensor heater fuse, or problem with the PCM, but if the other 3 sensors didn't have this appearance, I'd be suspicious of just the one sensor..
