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oxygen sensor related to coolant DTC?

398 Views 2 Replies 2 Participants Last post by  firehat
Any thoughts?
History.. I had a toasted cat. Was told my 02 sensors cat needed to be replaced by mechanic. I replaced the cat through the dealer under warranty but never changed the o2 sensors. engine DTC/CEL were cleared. all good for few months. then CEL on again. figured it was for the o2 sensors acting up so i replaced the front (precat) o2. (tip was real white) (150000km so figured needed it anyway). but CEL stayed on.
where i am now...
so i just ordered a rear o2 but i also bought a ELM scantool for my laptop and actually read the code which says only p2181 (coolant problem).
so i thought hmm either a) maybe the front o2 code corrected itself when i replaced it and the rear is fine, so now theres just this 2181 code. or b) the o2's were fine all along and i just have a 2181 code now. or c) the scan tool is missing some of the codes (unlikely).
data from the scantool:
short term fuel trim (bank 1): +1.6%
long term fuel trim (bank 1 ): +0.8%

intake air temp: 33 deg. C
Coolant temp: 68 deg. C

sensor 1 bank 1 : N/A
sensor 2 bank 2 : .475 V
this is the only data i have from the basic scan tool. the voltage on the rear o2 appears fine.
why is the front o2 sensor reading N/A ? if it was not connected properly, it should throw a code shouldnt it?
im not having any temperature problems that are noticeable. the car was not quite warmed up when i took readings. (temp gauge was about 1/4 way up. sits at dead centre when warm)
i dont know anything about fuel trim data just included it for FYI.
Aside from a possible thermoswitch/thermostat issue (p2181), i'm just wondering if i should be concerned about the N/A o2 sensor data? any logical explanation for that?
sorry for the long post, just trying to give adequate info.

2.0L golf 2003

Modified by firehat at 7:48 AM 3-20-2010
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Re: oxygen sensor related to coolant DTC? (firehat)

Have you searched p-2181 code??..there's like 5 postings that may help you. It's always good to do that 1st otherwise you could, and probably will, get spanked for not doing that.


Modified by 1955oval at 8:01 AM 3-20-2010
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Re: oxygen sensor related to coolant DTC? (1955oval)

roger, i did check out about the 2181, but i'm just wondering what the deal is with the o2 sensor voltage reading or if could somehow be related?
just wondering more if the no voltage reading may be normal or if theres a problem with it (dont get why theres no trouble code being triggered if there's a problem).
i got a bosch oem replacement sensor for the front but i read another post where someone had problems with them.
further to that, i read into the fuel trim readings and they are looking good from what i've read.
so everything seems to be running fine except theres no voltage reading.
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