2004 CATS, DESPARATION

[imp]

How does one know the cats are causing DTCs? At my wit's end, recurring code "HO2S Heater Resistance Bank 1 Position 2". Everything possible has been done to eliminate the O2 sensor as the cause, including completely re-wiring it after replacing all 4 sensors. Heater Resistance checks out just right. Even tried replacement PCM, same ****, over and over. First "drive cycle", after erasing DTC, drive ANY distance, no DTC, if engine not shut down. Reach destination, start back up, soon "P0054".

Experiencing this over and over, I beat on the cat with a hammer, while my wife kept eng. at 2500. NO CODE for over 1,000 miles. Came back. Beat again, no go, code comes back.

Truck runs perfectly, doing 18+mpg, no loss of power, believe can't be clogged cat.

Partially restrictive cat? See, heater resistance varies with temperature. If the exhaust gas stream has acceptable O2 content, but is not within expected temp. range, heater resistance will be affected. Did they program the DTC projection to throw that code, to indicate cat trouble? Nobody seems to know.......If the vehicle ran like cats were restricted, seems like you'd know, by performance degradation. Got PLENTY of power.

This has pissed me off to the limit of my tolerance. So, hoping somebody out there has had similar experience, solved the dilemma, or some damned thing resulting in solid info, I will consider, VERY RELUCTANTLY, to keep driving this wonderful performing Ex with the f**king CEL ON forever. Drawback?

Can't sell it. But, don't want to, anyway. 2004 4.0L 5R55S, 157,000 miles. Any help, ideas, greatly appreciated! imp

 

[boominXplorer]

What brand o2 sensor are you using? Same code before the O2 sensor swap?

 

[Hugh Janus]

https://www.obd-codes.com/p0054

 

[TechGuru]

Did you ever get ForScan? I believe you can view live O2 sensor data with it...

 

[imp]

What brand o2 sensor are you using? Same code before the O2 sensor swap?

@boominXplorer
I bought Walker sensors, replaced all 4, no change, same P0054 code thrown. All the suggestions in the link @Hugh Janus have been tried, none of the symptoms shown have ever been present. @TechGuru I have not yet gotten Forscan, but know I should. My code-reader is able to read live HO2S data, but not Heater Resistance or current level, heater voltage when ON is of course 12V.
One remark in the link doesn't make sense to me: "A code P0054 should be considered severe as it means that the upstream O2 sensor heater is inoperable." How can the downstream sensor's heater resistance have anything whatsoever to do with the upstream sensor's heater? The heaters are separate entities, separate from the data-measurement parts of the sensors. The statement is the same as saying two bread toasters side by side affect each others heat elements. If the UPSTREAM heater were inoperable, code would be generated indicating that. I have never gotten ANY code referring to either upstream heater, only downstream.

After checking even heater current with an ammeter (normal), I installed NEW WIRES to feed the Bank 1 Position 2 sensor, both Heater and Signal connections. You can guess the result, same code thrown. Even fed the heater off a different fuse; same ****. As I said, different PCM did same thing.

Here's a twist I tried for the hell of it, to get the sensor out of the direct gas stream. Threaded an "Ell" to fit the sensor bung in the exhaust pipe, to allow the sensor to stick out within the Ell above the gas stream, about 1-1/2". Amazing result, that threw a "HO2S Bank 1 Position 2 Stuck Lean" code PLUS the P0054! Hate like hell to replace the cat, only to learn it is not the cause. By now, I have little choice. What would the FORD DEALER do? imp

 

[boominXplorer]

I don't think it's a cat issue as it's more an electrical issue. Where have you tapped in to bypass the harness? The plug going into the computer could have a loose pin for that o2 signal.

The part where you got the stuck lean code shows its obviously connected somehow or sometime. I can understand how this one is frustrating.

 

[TechGuru]

Just something to throw out there...

Did you (unknowingly?) buy 4 identical O2 sensors? Because I believe either all 4 are different from each other or at a minimum the upstreams are different from the downstreams.

 

[imp]

Just something to throw out there...

Did you (unknowingly?) buy 4 identical O2 sensors? Because I believe either all 4 are different from each other or at a minimum the upstreams are different from the downstreams.

@TechGuru
Yeah, the fronts are most definitely different from the rears. In fact, the alignment tangs on the connectors are located such that upstreams can't plug into downstream's harness connectors, and vice-versa. Interesting note though, the replacement sensors I got have NO alignment tangs, meaning you could plug them into any accepting harness socket. I think they did this to service various makes and models without different plugs for each.

This is NUTS.

 

[Number4]

Clogged cats on the 4.0 usually burn a hole in the intake. Or can at least. I'd think the cats would be glowing red if there was an overheat issue with them.