Installed a BERK HFC and DOSKJOK (Amazon) OEM equivalent O2 sensor on 9/21/24. On 10/12/24 CEL came on with code P0141, which is: Oxygen Sensor Heater Circuit Bank 1 Sensor 2. Cleared the code and drove until 11/3/24 when the CEL came on solid again with code P0141. Cleared the code again and did the idle re-learn. Put the car away for winter and the CEL did not come back on, yet. As far as I can tell car is running perfectly and sounds a little off stock with new HFC, in a good way. '03 with the rest of the exhaust stock. Is the O2 sensor just junk?

 

Could be the sensor. I have seen many with twisted up cables from people removing them without disconnecting them from their harness connector and removing the wire clips so hopefully not the case here. The car will run normally as the secondary cat only monitors to see if he cat is doing its job. You should check that the wiring from the ECU to the sensor is in good shape just to be sure before replacing the sensor though.

 

Why'd you install the high flow car? When's your next annual smog test due? It ain't gonna pass with the CEL illuminated. Maybe in the spring put the OEM cat back, reset everything. First priority = pass smog. Optional = pass smog with the high flow cat. Lots of reports of folks swapping out exhaust systems routinely to pass smog. Five (5) bolts and 30 minutes under the car.

-- Chuck

 

The HFC is not causing the OP's CEL. The CEL is for a heater circuit malfunction in the sensor.
I ran a Berk for years with not on CEL
I even ran a hollowed out BERK in a pinch once for a couple of track days and it never set a CEL because the BERK has a built in O2 spacer in it.
I assume the OP put in the HFC because they wanted to, maybe the OEM one failed, etc.
If all they check for is the CEL then that will be fixed when the O2 heater malfunction is resolved.
I cannot say for sure the Berk would not pass a smog check to be honest. I have never lived anywhere that required a smog check. It may anyways but easy enough to swap it out once per year.

 

Not sure why problem solving is a difficult concept.

If you change a part and a warning suddenly comes up the part itself is the first suspect. Easy to rule out that first suspect: Put the original back and see if the problem remains. Don't cost nothing but a little time. Continue from there...

-- Chuck

 

The o2 sensors are delicate. If they are knocked around too much, it breaks the heater circuit in the o2.

Your o2 heater inside the sensor is broken, but making momentary connections to keep the light off.

A new sensor will cure it.

Because the rear sensor is not critical, and only measures catalyst activity, I use a Denso auto parts store o2.

 

What is the purpose of this comment?? Just trying to be condescending?

First you go on a tangent questioning their motives for installing an HFC and how are they gonna pass smog, etc. None of that addressed the question they are asking. Then you post this comment when we dont know if they even have the old sensor or what was wrong with it. One could simply say "hey do you happen to have the old sensor and can you try testing with that?" That is a valid question that may be helpful vs trying to act like someone is stupid to inflate your own ego. Believe it or not, many people have not spent years wrenching on cars (neither have you going by your posts by the way) and simply do not think of some things, that is why they come here asking questions. Just simply answer them and try to be helpful.

Maybe the old O2 was stuck in the old cat, maybe someone stole the cat and damaged or took the O2, maybe they did try this... we dont know this and could just simply ask.

 

Thanks for the input guys. My stock cat "brick" was vibrating/rattling mostly at idle, for a couple of years? I thought it was a heat shield at first but it got worse and my buddy and I put it up on our lift and he confirmed it was the brick while I ran the car through the rev range. I had already purchased the BERK to replace my stock cat. Then later in the season my CEL came on with several O2 codes. When I took it out it appeared the brick had broke the O2 sensor tip off? I did not twist the wires because I took the whole cat out first. I also reused both of the OEM wire clips on the new sensor wiring, which was almost twice as long as stock! Chuck, CEL did not come on right away after the install, took a bit over 2 weeks the first time and 3 weeks the second time. No smog in NY, just state inspection, but as you stated the CEL cannot be on if you want to pass. I'll go with Billman's diagnosis and replace the O2 sensor with a Denso. My only other question now is: Do I have to replace the exhaust gaskets on each end of the cat when I remove it to swap out the O2? I would think the "donut" one up front is re-usable but what about the rear one that came with the BERK?

 

The gaskets should both be reusable unless they appear damaged/cracked. Mine have been in and out multiple times for other jobs and are still just fine.

 

Thanks engifineer, I thought that was the case, just wanted to be 100%. The BERK came with a flat/foil gasket for the tail end, and as I'm sure you know the stock one is a crush ring that fits in a groove.
Also, little after the fact, but, I am the original owner and both the cat and O2 sensor were stock. Made it 21 yrs before failing! I also did some research here and read how you can lock down the cat media (brick, as I called it) with sheet metal screws? Again, a little too late, because I had already sold my old cat for scrap when I discovered that tip.