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Discussion Starter #1 (Edited)
Hi Folks,


If the throttle body is bad could it cause O2 sensors (bank1 sensor 2 and bank sensor 2) to act up and throw a CEL. I replaced the O2 sensor on one side but still getting code no heater circuit and other side I don't remember the description exactly but both were the O2 codes.


I ran a live data with my code reader and it was reading the O2s so not sure why it would say no heater circuit.


Any help is appreciated.....thanks.
 

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2001 Catera Sport, 1990 Porsche 944 S2 cab
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How about swap the O2 sensors, or the connectors if you can, and see if the code changes.
 

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Discussion Starter #3
okay, I'll try swapping the O2s not sure if that'll make any differences because my scanner with live data was reading it.
 

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2001 Catera Sport, 1990 Porsche 944 S2 cab
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I only suggest that as a starting point just to rule out the oxygen sensors. If the codes don't change, then you can rule out the O2 sensors. You can also check that you have 12vdc on at least one of the wires on the connectors. If you don't you might have a blown heater ckt fuse. The heater ckt is separate from the sensor ckt which would explain that you are still getting a reading from the sensor.
 

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Discussion Starter #5 (Edited)
Okay, thanks. How do I check for the 12vdc and where's this fuse located? Also, when the code P0161 (bank 2 sensor 2) came on at first I replaced the sensor with a new one from rockauto.com (APWI Part # AP4251) and then the next day CEL came on and it read two codes P0161 (bank 2 sensor 2) and P0140 (bank 1 sensor 2 heater circuit).

My question now is, could the new sensor (APWI part #AP4251) have cause this problem?

Thanks.
 

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2001 Catera Sport, 1990 Porsche 944 S2 cab
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First off, I see your getting codes 160 and 161?? My service manual shows both of those codes for bank 2 sensor 2. Did you replace the correct O2 sensor?

DTC P0160 HO2S Circuit Insufficient Activity Bank 2 Sensor 2
DTC P0161 HO2S Heater Performance Bank 2 Sensor 2
 

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Discussion Starter #7 (Edited)
sorry one of the code is P0140 instead of P0160

yes, replaced the O2 post cat (passenger side) bank 2 sensor 2 code P0160 came on first. The next day code P0140 came on so not sure what to do. I couldn't locate the fuse for the O2 either.


Thanks.
 

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Make sure the key is off, then disconnect the O2 sensor at the connector. Turn the key on. With the black lead of the mulitmeter, find a good ground point on the chassis. Connect the red led to one of the pins on the connector that goes toward the engine. Check the pins until you find one with 12vdc. This is the heater voltage from fuse 43 in the ECM. Check the connector of the sensor on the opposite side as well. (don't worry about the fuse just yet)
 

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Discussion Starter #9 (Edited)
Okay, thanks. I checked the voltage and getting 12vdc at both sides of the O2s so pretty sure the fuse is good. Also, the CEL came back on this morning after I turned it off last night. I scanned it this afternoon and it showed only P0140, bank 1 Sensor 2 heater circuit. Any idea where to go from here for this code?


Anyways, I swapped the sensors, cleaned the connectors and secured everything back. I'll let you know if CEL comes back on again.
 

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Discussion Starter #10
Okay, here is the update...

After swapping the sides on the rear O2 sensors we drove around and there was no CEL. Then this morning the CEL came back and it read the same two codes P0140 - O2 Circuit No Activity Detected Bank 1 Sensor 2 and P0161 - O2 Heater Circuit Bank 2 Sensor 2. I checked voltage last night and it was reading 12Vdc at both connection.

Also, when I checked the resistance on the old O2 sensors it was showing 8.5 each whereas the new one from rockauto.com APWI part #AP4251 was showing a resistance of around 13.

I have no clue what to do now, either get another sensor for the other side and see if it'll fix the O2 issues or track some other problem in the system.

Also, should I stick with Bosch brand O2s or the APWI will be fine? I checked with rockauto and they said they have been selling APWI O2 brand for the past year and had no problems.


Thanks.
 

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May be a "stupid" question, but are you clearing the codes after replacing the O2 sensors?

IIRC, once a code is set, it stays in memory until cleared. (That used to be the case, I haven't thrown a code in several years!)

It's worth a try.
 

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Discussion Starter #13
Any other tips what I should do to figure out these rear O2 CELs, should I buy another sensor?


Thanks.
 

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these cars are definitely not happy with many aftermarket O2 sensor brands ... bosch sounds like it might have been the OEM supplier but i can't remember

stick with the ACDelco part if you can
 

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Just to clarify, on the sensor with the 161, with the old sensor, new sensor and the sensor from the other side on the connector, you are always getting code 161? What percent or voltage does your scanner read for the sensors. Is the new sensor a direct fit or universal?
 

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Discussion Starter #16
The new sensor is a direct fit and per rockauto.com, these are compatible and also fits perfectly. This is new brand and have sold a few of these sensors in the past year and had no problems. The voltage shows 12vdc at the connector end when I turn on the battery. I believe it's the resistance that shows 8.5 on the the old ones and the new one I got shows about 13.

The P0161 was there before changing the sensor, so got the new sensor and now I get codes P0161 and P0140 after the replacement. i swappd the sides and still get the same codes.

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I'm going to try one more thing, going to install the old sensor back, clear the codes and test drive it. If the CEL comes on I'll scan it and see what it shows. If it's just P0161 then I'll return APWI brand sensor and go with Bosch or AC Delco brand sensor.
 

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So, with 3 different sensors in bank 2 sensor 2, one of them being new, you always get code 161. I would say there is probably something else wrong. From the connector toward the ECM, or an exhaust leak upstream or the air distribution system. (from the service manual)
There are more tests you can do. There is a detailed troublshooting guide in the manual for all the codes.

For code 161 I'm summarizing from the manual.
Key off for at least 20 min. meter on ohms, red led to pin 3, black led to chassis ground. should be less than 5 ohms.
Key on, meter on VDC, red led to pin 1, black led to pin 2, should be 0 vdc
Start engine, meter on VDC, red led to pin 1, black led to pin 2, should be 12vdc or switching between 0 and 12v.
Engine off, jumper a wire from pin 4 to chassis ground. Key on, Engine off, scantool should read 0 volts (or 0% I would imagine) for the affected sensor.

Also, on the sensors, read the ohms between pins 1&2(the heater) then 3&4(the sensor), and compare them between the sensors.



1
RED/BLU
AP950
Fused Battery Feed

2
BRN/WHT
XM950
HO2S Heater Control

3
BRN/GRN
XU960
HO2S Reference Ground

4
BRN/BLU
XP960
HO2S Signal
 

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Discussion Starter #18
Okay, will try it out. I don't think there's any exhaust leak bit will check again. How many ohms should it read between 1 & 2, 3 & 4?

Thanks.
 

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Don't know, but I'm heading to the junkyard now to get a sensor for mine, sensor #1. I have a code 135. When I put it in later I can check my sensor #2 and let you know.
 

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Discussion Starter #20
Okay, thanks. I swapped the new sensor out and installed the old one back. Now both are the old sensors on the car. I check the resistance again on the old sensors and it was 8.3 to 8.5, the new one was 13.3.

I scanned it with live data check and it was reading same numbers at both sensors so pretty sure both sensors are okay. Also, checked the connectors and getting 12vdc.

Well see what happens now.

Thanks.
 
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