bad 02 readings

[HiTechRedNeck73]

ok, here is what I found in my Factory Service Manuals...

P0031 - o2 sensor 1/1 heater circuit low
P0051 - o2 sensor 2/1 heater circuit low
P0136 - o2 sensor 1/2 heater relay circuit open or shorted
P0152 - o2 sensor 2/1 shorted to voltage
P0175 - o2 sensor 2/1 fuel system rich
P0460 - fuel level unit, no change over miles

my opinion is such...

P0031 & P0051 are related, and I had a similar problem recently... there is a 5-volt regulated power supply in the PCM that supplies all the sensors a basic 5-volts to operate. my front sensors were throwing this code just as yours are... I thought there was something wrong with the front sensors... but after changing them, the code remained. after looking at the wiring schematics, I discovered a flaw in Chrysler's design... the 5-volt power tap used by the o2 sensor heaters goes to the rear sensors first and then to the front... this is important because the sensors heaters are electric resistance heaters... for if your resistance is too high in the rear it will supply too much voltage to the front and if resistance is not enough, then there will be a shortage of voltage up front... because electricity travels in the path of least resistance... well, after pulling the rears, I discovered that they were the wrong sensors for my year... after 2002, Chrysler vehicles have different front and rear sensors... they are not universal after 2002... so I caution you to check your rear sensors...

P0136 & P0152 you found with the blown fuse... don't know what happened there, but may be related to your adjustments

P0175 is a no brainer

P0460 is very interesting... it took me forever to find it... Chrysler PCMs store MPG in the computer for use of overhead readouts or the use of a DRBIII (Chrysler's proprietary ODB reader)... the reason it's so interesting is that usually only MAF-based cars have MPG in the computer... MAF-based systems can calc MPG on the fly... Chrysler doesn't use any MAF systems, they are MAP-based engines (usually no MPG being calc)... it's what allowed them to get the EPA to allow them to build cars without EGR valves, of which they have not had since 2002. they showed the EPA that their engines had less emissions without and they were given special permission to remove them... it was a very cool thing... anyway, sorry to get off topic... so the computer actually monitors the level in the tank as part of the mileage... I'm going to check into this further... it's very interesting... basically, it looks for a certain amount of change in the tank after so many miles... I don't know what those variables are, but I will find them and post the info... so if you took a Chrysler vehicle and got it to 100% hydrogen, or even just beyond what the computer expects, then it will throw this code... so much for having hho and no codes...

I will keep you posted on any more I find...

[HiTechRedNeck73]

P0460...

>0.1volt change in ________ measure of time in idle

>0.1765volt change in ________ miles while driving

looks as if the voltage from the tank sender is lower on full and raises as the tank empties... since the voltages listed didn't have a + or - sign on them in the manual...

I did find this info in the FSM after my last post... there is a proceedure to test the reading, but it references a manual I don't have in front of me... I'm still looking... but since these are settings in the PCM based on engine, it means they can be programmed to a different setting...

really great stuff... this confirms something I've been fighting my local mechanic about... thanks for bring it up...

[hg2]

Hitechredneck you said dodge hasn't had egr valves since 2002.My dodge truck is post 2002 and I had to replace my egr valve last year.Where did you read this,just curious?

[richardb200373]

Redneck, thank you for looking up all that information, very generous of you using time and skills on this. I only reset my computer for a minute after the engine light went out, so maybe if I take the negative off for a while, it will take away the 31 and 51. In all this same time is when I replaced the 02 sensors also (last night). As for 136 and the other ones, I did pierce the wire with my multimeter to test, which I probably should'nt have done, don't know if this is hurting it or not or if that is what is giving off these signals.
As for the different 02 sensors, you are right. They call them universal, but there are 2 different types for front and rear. I guess the universal is for different cars. I think the part numbers are 15029 (front) and 15030 (after cat) for Bosch sensors from auto zone. That was also part of my mix up was the wrong ones were given to me.
Well, I'm getting closer, at least the engine light is off, now just need to fine tune. I stopped for coffee last night while test running (turned jeep off) and my vinegar in the bubbler got sucked into my tank which has 1/2 cup Koh to one gallon distilled water, so that is all mixed up, going to have to drain again today. It was still producing but not quite as much. My cell is pushing more out than fluid going back in (dry cell). I have 2 tubes up top and only 1 on the bottom, I should probably switch them around. I think a longer hose to the bubbler will take care of my sucking back in problem. Sorry to get off subject.
Anyway, how much should I be adjusting my efie at a time, 0.01, 0.05?
Thanks again for your help and thank you for looking up those codes.

Oh, also forgot to add, my jeep has the mileage display on it - it does average, instant mpg, and distance to empty, I remember you said something about this and the MAP I think. It seems to be some what close. It's hard around here with the hills and mountains. I just need to get on the road for a day and do some testing.
Thanks again.

[HiTechRedNeck73]

Hitechredneck you said dodge hasn't had egr valves since 2002.My dodge truck is post 2002 and I had to replace my egr valve last year.Where did you read this,just curious?

I was under the impression that is was all chrysler vehicles... my 2004 Intrepid doesn't have one and my dad's 2006 Ram w/Hemi doesn't have one... I don't know what to say... it was an article posted on the EPA's website if memory serves... someone mentioned it on another site and I went looking for proof after I noticed that my own car didn't have one... I will find the article and post the link...

[hg2]

I was under the impression that is was all chrysler vehicles... my 2004 Intrepid doesn't have one and my dad's 2006 Ram w/Hemi doesn't have one... I don't know what to say... it was an article posted on the EPA's website if memory serves... someone mentioned it on another site and I went looking for proof after I noticed that my own car didn't have one... I will find the article and post the link...

I know because the first code my truck set was egr and it was located on the front of the head on the passenger side.The truck was under extended warrany and I remember the valve was less too buy than my $100 deductible,and took about 20 min. to replace.

[HiTechRedNeck73]

I know because the first code my truck set was egr and it was located on the front of the head on the passenger side.The truck was under extended warrany and I remember the valve was less too buy than my $100 deductible,and took about 20 min. to replace.

what year and engine... I don't recall any EGR valves on the front head area of the chrysler engines...

the purpose of an EGR valve is to dump unburned exhaust fumes back into the intake system to pass through the engine again... are you sure we are talking about the same thing...

usually they are in the rear or on the side... they will have a tube that comes off the exhaust or an exhaust port on the head and the other side will connect to the intake or plenum in some way... also strange that is was less than $100... usually those things are more than what they are worth...

I've not found the article yet, but I will, just have to remember the way I found it in the first place... it's been quite a few months and it's just not jumping out at me...

[hg2]

what year and engine... I don't recall any EGR valves on the front head area of the chrysler engines...

the purpose of an EGR valve is to dump unburned exhaust fumes back into the intake system to pass through the engine again... are you sure we are talking about the same thing...

usually they are in the rear or on the side... they will have a tube that comes off the exhaust or an exhaust port on the head and the other side will connect to the intake or plenum in some way... also strange that is was less than $100... usually those things are more than what they are worth...

I've not found the article yet, but I will, just have to remember the way I found it in the first place... it's been quite a few months and it's just not jumping out at me...

It did have an exaust tube coming up from the rear of the head leading to the front.The shop that read the code for me was one of my customers and he said they were about $300,and he also comented that sounded cheap when I told him how much it cost for one.I got at the dodge dealership.

[HiTechRedNeck73]

It did have an exaust tube coming up from the rear of the head leading to the front.The shop that read the code for me was one of my customers and he said they were about $300,and he also comented that sounded cheap when I told him how much it cost for one.I got at the dodge dealership.

wow, you got a great deal considering it came from the stealership...

[hg2]

wow, you got a great deal considering it came from the stealership...

I just called the dealership and the part number is 53032-509AM and they 're $80.56 now,I guess they went up like everything else.This was about 2 years ago when it went bad.