O2 heater circuit resistance P0057, p0161

[Nomorejags]

Hello everyone. I'm new to the forum.  I have an 08 Cayenne Gts that has catalytic converters that have failed so I built and installed an o2 sensor simulator to fool the DME.  Seems as though it is working properly but after installing I started getting a p0141 and p0161 basically that there was an issue with the heater circuit.  I tested the circuit and everything seems fine so I assume it is the heater element failing.  

 

I would like to know if anyone can please share with me the correct resistance for the o2 heater circuit ( two white wires on the sensor).  Normal rules would imply that it's 8ohms and anything outside ~10% would kick a code.  I installed one new Bosch sensor and the resistance is 9.8ohms and the one I didn't replace (I'm assuming it's stock) is 9.6ohms.  I built a resistor circuit that could handle 40watts and is ~11. 5 ohms (got this fix from the lexus forum). However now I'm throwing a p0057 and p0037 for circuit low voltage. 

 

If someone could share with me the correct resistance for the heater circuit I believe I can sort this out and go pass inspection :). Thanks.

[Nomorejags]

Please? Anyone with a working o2 sensor, a multimeter, and a few minutes I'd greatly appreciate your input. Thanks!

[Loren]

P0037 Oxygen Sensor Heating Output Stage After TWC, Bank 1 – Below Limit

 

Possible fault cause:
- Short circuit to ground
- Oxygen sensor faulty (short circuit to sensor casing)
- DME control module faulty

 

P0057 Oxygen Sensor Heating Output Stage After TWC, Bank 2 – Below Limit

 

Possible fault cause:
- Short circuit to ground
- Oxygen sensor faulty (short circuit to sensor casing)
- DME control module faulty

[Nomorejags]

Thank you for your reply. I am aware of the description of the DTC I have Alldata, Mitchell etc. However, correct me if I am wrong, this code would also be given if the resistor I have in the heater circuit is too high. Currently Im using a 25w 11ohm resistor. I would like to know what is the proper resistance for the heater circuit. I dont have a known to be good or new oem oxygen sensor to test. Ive heard 8ohm is the normal resistance for a heater circuit. However I know this isn't true for audi and at least some bmws so I feel that is the case here. Thanks again for the reply.

[JFP in PA]

Couple of points:

 

1. The resistance reading spec on the circuit you are working with is infinite resistance per the OEM service manuals.
2. Instead of screwing around and trying jury rig a fix to defeat the system, why don't you just repair or replace the sensors if they are bad?  They are not that expensive, and relatively easy to replace if they are actually bad.  Your problem could be as simple as a connector or wiring issue.

[Nomorejags]

Thanks Jeff.

 

1. You have a service manual? Thanks for the input but Im sorry the heater circuit inside the oxygen sensor can not be of infinite resistance. Are you reading the resistance for the heater control circuit in the DME? That would make a little more sense. Im looking for the resistance of the heater inside the oxygen sensor.

2. I have replaced one of the oxygen sensors however still throws a p0161. I believe this is because I purchased the universal bosch sensor that was "said" to work for our vehicles. Sure, I could go buy a sensor if that's the issue but I would like to confirm this new sensor isnt just incompatible and the easiest way of doing that is knowing the resistance of a known working oxygen sensor. If this were an in stock item I'd just walk into Autozone with my mulitimeter and ask for one off the shelf  (as done before, lol).

 

Defeating the system is kinda my forte. I go this deep on most of my vehicles. I've already tested the connectors and harness and they tested fine.

 

The only other vehicles I have been able to find that threw these codes after installing an 02 sensor simulators are Lexus/Toyota. And oddly enough I was able to find the following information last night from their service manual. Would you happen to have something similar for Porsche. Id be very interested in seeing it. Thanks again for your help.

 

[JFP in PA]

From the OBD II diagnostics manual, read it and weep:

 

 

You most likely have an incompatible O2 sensor, which is why it is always a good idea to go with the correct parts.  Good luck defeating the system.....

[Nomorejags]

Thanks for posting.  However,  if you take a second look at the procedure you just posted it does not list the heater circuit resistor as infinite resistance.  I'm unable to tell how the pins are being numbered because there is no picture shown,  however I can tell you that the pins to check resistance thru would be pins 1 and 2 or 3 and 4 (depending on how you're looking at the plug). It's not possible for a working heater circuit to show infinite resistance.  

 

Thanks for the luck.  If I can beat Maserati and their f1 system I'm not too worried about an oxygen sensor it's not that complicated I'm just lacking resources.  I did purchase what was supposed  to be the "correct"  sensor.  I didn't just pick one at random.  Bosch is the OE  equipment and I used the universal Bosch sensor that is listed for our vehicle.  But this wouldn't be the first time a universal sensor doesn't work. 

 

I called my buddy with a panamera if I can't figure this out on my own he'll try and swing by this weekend and I'll be able to figure it out. 

 

Either way I'll be be sure to post my results back here for any other Do-it-yourselfers going thru cat deletes but not planning on getting the entire DME remapped and o2 extenders just aren't working. 

[JFP in PA]

8 minutes ago, Nomorejags said:

Thanks for posting.  However,  if you take a second look at the procedure you just posted it does not list the heater circuit resistor as infinite resistance.  I'm unable to tell how the pins are being numbered because there is no picture shown,  however I can tell you that the pins to check resistance thru would be pins 1 and 2 or 3 and 4 (depending on how you're looking at the plug). It's not possible for a working heater circuit to show infinite resistance.  

 

Thanks for the luck.  If I can beat Maserati and their f1 system I'm not too worried about an oxygen sensor it's not that complicated I'm just lacking resources.  I did purchase what was supposed  to be the "correct"  sensor.  I didn't just pick one at random.  Bosch is the OE  equipment and I used the universal Bosch sensor that is listed for our vehicle.  But this wouldn't be the first time a universal sensor doesn't work. 

 

I called my buddy with a panamera if I can't figure this out on my own he'll try and swing by this weekend and I'll be able to figure it out. 

 

Either way I'll be be sure to post my results back here for any other Do-it-yourselfers going thru cat deletes but not planning on getting the entire DME remapped and o2 extenders just aren't working. 

 

My point is that it isn't necessary to delete the cats, remap the DME, or mess with O2 extenders, you just need to use the correct sensors and everything will probably be just fine..........

[Nomorejags]

I see what you are saying. I believe you dont fully understand my current situation. My cats have already been deleted. A set of new sensors will do nothing but throw a p0421/p0431 for bad cats. At the very least I would need an o2 simulator and a set of new sensors. My personal issue is that I kind of have a problem dropping $300+ on a set of sensors that's actually doing nothing besides fooling the heater circuit. I could just build a resistor for that purpose. This is not an uncommon practice its just that the specs for our oxygen sensor must not be the standard 8ohms. I'm assuming it's somewhere in the 3.5-7ohm range based on my results so far. 

Edited December 16, 2016 by Nomorejags

[lewisweller]

On 15 December 2016 at 3:35 AM, Nomorejags said:

Hello everyone. I'm new to the forum.  I have an 08 Cayenne Gts that has catalytic converters that have failed so I built and installed an o2 sensor simulator to fool the DME.  Seems as though it is working properly but after installing I started getting a p0141 and p0161 basically that there was an issue with the heater circuit.  I tested the circuit and everything seems fine so I assume it is the heater element failing.  

 

I would like to know if anyone can please share with me the correct resistance for the o2 heater circuit ( two white wires on the sensor).  Normal rules would imply that it's 8ohms and anything outside ~10% would kick a code.  I installed one new Bosch sensor and the resistance is 9.8ohms and the one I didn't replace (I'm assuming it's stock) is 9.6ohms.  I built a resistor circuit that could handle 40watts and is ~11. 5 ohms (got this fix from the lexus forum). However now I'm throwing a p0057 and p0037 for circuit low voltage. 

 

If someone could share with me the correct resistance for the heater circuit I believe I can sort this out and go pass inspection :). Thanks.

Are you looking for pre or post cat sensor resistance reading? They are different. 

I got a new Bosch oem precat sensor which I will install tomorrow on my 2006 ctt. I will measure the heat circuit ohms for you. 

FYI you bought the wrong sensor but I admire your efforts to find a work around. Kudos if you fix it and reach for the wallet if you can't. 

[lewisweller]

Resistance of the heater circuit is 2.9ohms measured across white and grey wire terminal 3 and 4 respectively. 

[lewisweller]

New sensors Resistance of the heater circuit is 2.9ohms measured across white and grey wire terminal 3 heater - and terminal 4 heater + respectively. 

 

Old sensor measured 3.7ohms. 

 

(Bosch LS7174, 5 wire lambda sensor)

Edited December 24, 2016 by lewisweller

[lewisweller]

Nomorejags you gone awol?

 

[Nomorejags]

Hey there thanks for all the input. I've been a bit tied up for the holiday. I was looking for the resistance of the post cast sensor but thank you for posting the pre-cat I was unable to find that on the internet also so hopefully someone can now benefit from the info. I was able to get my hands on a new Bosch post cat sensor. Resistance measured 9 ohms exactly. I plan to wire up the circuit with a 9ohm 20watt resistor and see if that does the trick for me. Ill be sure to post back with results. May I ask what code you were getting that led to the replacement of your sensor? Thanks again.

[lewisweller]

12 minutes ago, Nomorejags said:

Hey there thanks for all the input. I've been a bit tied up for the holiday. I was looking for the resistance of the post cast sensor but thank you for posting the pre-cat I was unable to find that on the internet also so hopefully someone can now benefit from the info. I was able to get my hands on a new Bosch post cat sensor. Resistance measured 9 ohms exactly. I plan to wire up the circuit with a 9ohm 20watt resistor and see if that does the trick for me. Ill be sure to post back with results. May I ask what code you were getting that led to the replacement of your sensor? Thanks again.

No codes really. I once got a lean code for bank 1 whilst having a vacuum pipe leak. But once fixed the code erased and never returned. I diagnosed the bad sensor by graphing it on vcds and it was apparent the milliamp value was low and also during snap throttle it wouldn't go up to a peak rich value which means it's a "lazy" sensor with slow and reduced performance. 

After replacement the bank 1&2 sensors are like mirror images and follow each other perfectly. 

I'm still struggling to get to the bottom of stuttering misfire when engine is warm. Throttle body is whining which is suspect.