P0052 - 5.7 - heater circuit high - new sensors

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Eel_Dahc

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I'm trying to figure out why I keep getting the P0052 HO2S Heater Circuit High (Bank 2, Sensor 1)

I replaced both bank 2 sensors with NGK/NGT replacements. I was getting circuit high for both but now only sensor 1 is giving the code.
I cleaned all grounds under the hood. I ohmed out the ground and I get a good ground at the O2 plug port. It's a white wire on the sensor and had me confused at first. I get get a good connection from the harness O2 plug to the C2 PCM plug for the heater. PCM Pin 17 for heater. None of the harness wires had continuity between them. 800 or so ohms maybe on 2 of them. The new sensors have 5 to 6 ohms resistance between ground and the heater wire.

I have one of those bluetooth scan tool things and I've been running an app that shows the 02 sensor levels and voltages.
I noticed that the bank 2 sensor 1 would stay at 1.27v for quite some time while the others went down fairly quickly when engine runs. All four start out at 1.27v when cold.
It does not specify if the 1.27v is for the heater or the sensor.

BTW Battery disconnected every time I disconnect or reconnect the O2 sensors. I also connect the pos and neg cables together for a bit to drain it.

I then swapped B1S1 with B2S1 cleared codes and ran it again.

I still get the code and the B2S1 still shows 1.27v longer than the others do. I am guessing that the sensor isn't heating up on it's own and voltage goes down with heat from the actual exhaust.

I haven't done it yet but I plan to cut the old sensor plug off so that I can attach my meter to the wires to test the voltage.

If it turns out that the PCm has a problem and isn't sending enough juice to the heater for that sensor, would it be wise to tap into one of the other sensors to bring the voltage up? I think it's supposed to be 12v.

Took the old sensor plug and put a light bulb on the heater wires, the bulb does not light up on B2S1 but does on B2S2. ALthough, the sensor was removed as well, may try again with the sensor attached tomorrow.

Thanks

1/31 I wired the old 02 sensors' heater control wires together and put those back in, so now 12v comes from s2 to s1. Now S1 heats up quick enough to not throw fuel trims too far out of whack. Guess I need a new PCM.
 
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Eel_Dahc

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Edit button is missing so I'll update here.

This was my dad's truck. The truck started acting up were it would miss, backfire and lose power. Took it to a mechanic. They replaced the 02 sensors. truck ran fine for a week and symptoms came back. Noticed that if I reset the battery, truck would run fine. Took to another mechanic and they replaced the fuel pump. Same thing, a week later it was acting up again. I saw a pattern. So whenever it would mess up, I'd reset the battery and have been doing this for about 8 months. Well I got tired of that and knew that the truck deserved better so I bought one of those cheap obd ii bluetooth plug ins and using an app found that the fuel trims were crazy on bank 2 and that heater circuit had codes. Went researching the internet and most things say ground which I cleaned them all. They also say fuses or relays but not on this truck, it's either the o2 sensor or the pcm. Figured out how to test the sensors and they were good but they were bosch so I ordered NGK as many suggest. Well same results with those. Then I researched the wiring and finally tracked the problem to the pcm not putting out the 12v for the b2s1 heater. Took the bosch sensors and made a pigtail between the heater wire to bring power from b2s2 to b2s1.

Truck has been running fine now but I will be stuck with that check engine light because that heater circuit is still bad. I'm going to run it like that for as long as I can and in the meantime see about getting a new computer. If I get one I'm tempted to take this one apart and see if I can find the problem.
 

LoneWolf3574

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Not that it may help you on this matter much, but I had weird electrical gremlins that would come and go. I found the ground on the rear of the heads (3 points, LH head, RH head, cab) to have been cut between the RH head and the cab. Once I replaced that ground, I'd say 99% of my odd electrical gremlins went away. Just a suggestion on checking that ground.
 

Recoil

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Not that it may help you on this matter much, but I had weird electrical gremlins that would come and go. I found the ground on the rear of the heads (3 points, LH head, RH head, cab) to have been cut between the RH head and the cab. Once I replaced that ground, I'd say 99% of my odd electrical gremlins went away. Just a suggestion on checking that ground.
LoneWolf is absolutely correct - check ALL your grounds and clean/fix/replace them to see if that helps.
 
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Eel_Dahc

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Not that it may help you on this matter much, but I had weird electrical gremlins that would come and go. I found the ground on the rear of the heads (3 points, LH head, RH head, cab) to have been cut between the RH head and the cab. Once I replaced that ground, I'd say 99% of my odd electrical gremlins went away. Just a suggestion on checking that ground.

Thanks.

I went through every ground that I could find. It was odd how the rear sensor worked but not the front because it's the same wire going to ground. I made extension wires for my meter and ohmed the wires, they were all good with low ohms. I even added a light bulb to load test and from the PCM connector to the sensor appeared fine.

The pcm is just not putting out 12v for that first sensor heater.

After I spliced the first sensor into the second one's 12v heater wire, the truck has ran fine. Over 300 miles now, no backfires, no rough idle.

So to help other----- Having that little $10 bluetooth adapter and the InCarDoc phone app allowed me to see the fuel trims. I could see why it was running like crap.

3 sensors came on straight away (self heating) when starting the engine and had good numbers while the problem one would only kick in and give good numbers once heated up by exhaust heat.

The computer would learn those junk fuel trims. That's why it would always run fine once I unhooked/rehooked the battery until it relearned again. Rinse repeat.
 
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Eel_Dahc

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In case anyone ever has this problem and finds this post. Truck is still running fine with 1 O2 heater wire connected in parallel to a wire from the other one behind it because the computer has a problem and doesn't send power to the O2.
 

1SLwLS1

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D a m n, this sounds like a problem I have been having for a couple of years (looking at old data logs) but only recently noticed and started to tackle - truck has a SRT 392 with small cam (rough idle and rich fuel due to off-road y masked the fact that there was a problem), I didn't notice STFTs on B2 were 0 as I was monitoring B1 and went to recently start tightening up VE tables but noticed STFTs on B2 are always 0.

My B2 heating circuit is non-existent (both S1 and S2) and I show 0 STFTs for B2. Only when the sensor naturally heats up does it start to show expected voltage less than 1 but for some reason, the computer is not trimming fuel to correspond, maybe because it is not heating it so it is not using feedback. I also don't have any codes relating to the heating circuit, but I did just turn those back on, guessing original idiot tuner just turned them off instead of identifying and fixing the problem. This past week I slowly identified the heating circuit as the culprit or at least a definite issue relating to no B2 STFTs and was about to begin diagnosing the wiring on the heating circuit this weekend.

On our trucks O2 heating circuit, 12V (unfused?) is supplied to the sensor and the PCM controls the ground, is that correct? I need to find the diagrams for my truck, was hoping to avoid a monthly alldata fee but that may be necessary.
 

1SLwLS1

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D a m n, this sounds like a problem I have been having for a couple of years (looking at old data logs) but only recently noticed and started to tackle - truck has a SRT 392 with small cam (rough idle and rich fuel due to off-road y masked the fact that there was a problem), I didn't notice STFTs on B2 were 0 as I was monitoring B1 and went to recently start tightening up VE tables but noticed STFTs on B2 are always 0.

My B2 heating circuit is non-existent (both S1 and S2) and I show 0 STFTs for B2. Only when the sensor naturally heats up does it start to show expected voltage less than 1 but for some reason, the computer is not trimming fuel to correspond, maybe because it is not heating it so it is not using feedback. I also don't have any codes relating to the heating circuit, but I did just turn those back on, guessing original idiot tuner just turned them off instead of identifying and fixing the problem. This past week I slowly identified the heating circuit as the culprit or at least a definite issue relating to no B2 STFTs and was about to begin diagnosing the wiring on the heating circuit this weekend.

On our trucks O2 heating circuit, 12V (unfused?) is supplied to the sensor and the PCM controls the ground, is that correct? I need to find the diagrams for my truck, was hoping to avoid a monthly alldata fee but that may be necessary.
Just FYI for anyone that runs across this issue, one possibility (in my very particular case), was the original tuner turned off both oxygen sensors on bank 2. With them turned off, there is no need to heat them and hence started my issues.

Instead of lugging around my cumbersome laptop, last year I bought a surface pro to do tuning and logging and installed the latest version of HPTuner's VCM Suite. In the latest version, the option to enable/disable specific sensors is not visible (EPA). I had scoured over everything in the tune and couldn't find anything and ran multiple diagnostic tests, continuity, circuit degradation, circuit isolation and load testing, heater tests, etc., and had about eliminated every possible variable with the only remaining option being a faulty PCM. Fortunately the logistics of replacing the PCM for my particular setup (HPT credits, latest OEM tune, 8 speed swap transmission overrides, etc.) would be cumbersome and led to great procrastination on my part. I posted the issue and several pieces of evidence on the HPT forums weeks ago and luckily someone stumbled across it yesterday and thought to check the tune I posted with their older version of software and saw that the sensors were turned off.

Anyway, this is probably a very unlikely solution to anyone who stumbles across this in the future, but I always like to follow up with found solutions, regardless of how likely they are for someone else...just incase.
 
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Cerd

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On my 2003, I was having a similar problem, but mine came down to G107 (upper right corner of the engine bay on the firewall (upper left if looking from the front)). I took the nut off and polished up the stud and terminal with a steel brush for a Dremel and it worked fine after.
 

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