# Symptoms of a bad oxygen sensor!



## 1993jetta GL (Sep 17, 1999)

Well I have about 100k on the engine and have never had the Oxygen sensor replaced and am just curious what some of the symptoms are of it going bad! I know the computer will go into limp mode and the car will still drive!
My car seems to be running rich when cold and smoking ( or bad valve seals) and my car is getting bad gas milage! also my car seems to be pinging a little under light acceleration! any help would be appriciated Adam also my car doesn't burn Oil!


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## Red Baron Golf (Jul 18, 2000)

*Re: Symptoms of a bad oxygen sensor! (1993jetta GL)*

Sounds like you got a bad sensor for sure, but make sure there isn't anything else wrong. Is it throwing any CEL's?
You basically described the symptoms yourself.


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## timmybgood (Dec 12, 2001)

*Re: Symptoms of a bad oxygen sensor! (Red Baron Golf)*

when my O2 went bad my car just stopped running...


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## golfracer04 (Aug 1, 2001)

*Re: Symptoms of a bad oxygen sensor! (Red Baron Golf)*

About 4000 miles ago, my CEL came on. This was just about the time I turned 100K. I have had no noticable problems with the engine other than some less-than-wonderful gas mileage. A friend of mine said that he thought it could be the 02 sensor. Is there any way I can check without having to pay for a diagnostic?


[Modified by golfracer04, 12:09 AM 7-24-2002]


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## DoublFeliX (Jul 27, 2001)

*Re: Symptoms of a bad oxygen sensor! (golfracer04)*

Run a search for O2 Sensor, I remember a thread at some point that goes into more detail, but I believe you can pull the O2 sensor out and tell by coloration (if sensor is chalky looking it's worn out) whether it's still good.


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## engine101 (Apr 8, 2002)

*Re: Symptoms of a bad oxygen sensor! (DoublFeliX)*

FYI, there are 2 O2 sensors. One pre-catalytic and one post-cat. They are practically right next to each other and look identical.


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## Bill95GL (Sep 5, 2000)

*Re: Symptoms of a bad oxygen sensor! (1993jetta GL)*

The symptoms sound like they could be due to a bad oxygen sensor. In any event, at 100,000 miles, it would be a good idea to replace it anyway. My car has 81,000 miles, and I just checked the sensor according to the voltage tests in the Bentley manual.
Pulling an injector plug and pulling the vacuum hose off the fuel pressure regular tested OK for high and low voltage response, but with everything hooked up normally, the voltage pulses took two seconds to go up and two seconds to go down (oscillating between .3 and .7 volts). It ought to be more like a pulse every half second. A bad oxygen sensor that produces a too rich mixture can ruin tha catalytic converter ($!).


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## PowerOverFC (Jul 24, 2002)

*Re: Symptoms of a bad oxygen sensor! (Bill95GL)*

arent there only 2 O2 sensors on post 96 models (the OBD2 switch) ????


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## PowerOverFC (Jul 24, 2002)

*Re: Symptoms of a bad oxygen sensor! (PowerOverFC)*

or did VW do that early? in 93


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## 1993jetta GL (Sep 17, 1999)

*Re: Symptoms of a bad oxygen sensor! (PowerOverFC)*

I will throw the new sensor in tomorrow and I will let everyone know if that was the problem! also I think there is only one Oxygen sensor on the OBD1


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## Biggie (Mar 21, 2002)

*Re: Symptoms of a bad oxygen sensor! (1993jetta GL)*

quote:[HR][/HR]... also I think there is only one Oxygen sensor on the OBD1[HR][/HR]​Correct. 2 in the OBDII.


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## engine101 (Apr 8, 2002)

*Re: Symptoms of a bad oxygen sensor! (Biggie)*

While we're on the subject, has anyone tried a replacement sensor other than the $80+ Bosch ones?


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## Biggie (Mar 21, 2002)

*Re: Symptoms of a bad oxygen sensor! (engine101)*

I think you can get cheaper ones if you don't mind soldering....
By that I mean I think you can buy them without the connector.


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## SILVERADO (May 16, 2002)

*Re: Symptoms of a bad oxygen sensor! (Biggie)*

Don't use anything but Bosch sensors,you'll be sorry.....And if your o2 sensor was bad it would throw a code.


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## purevw2 (Jul 27, 2002)

*location of a sensor*

can you tell me where the o2 sensors located in an 00 jetta?


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## FSUJetta (Jul 8, 2002)

*Re: location of a sensor (purevw2)*

basically the same place as the 96 jetta described above. pre cat and post cat i belive


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## 1993jetta GL (Sep 17, 1999)

*Re: location of a sensor (FSUJetta)*

I repaced the sensor today and it totaly fixed my car! the car runs perfect! I have been driving the car around for about 2 years with these problems , I just fugured my engine was getting old and eaven on my last birthday bought a intake to mask the sound of the slight pinging! these sensors must just take a wile to go out and its so gradual you cant eaven tell untill your car starts smoking at startup under acceleration and gas milage slightle gets worse and the engine sounds like a wrist pin is loose and knocking under light acceleration! I must not have a check engine light being its a 93 but I bet if I would have had the shop run the codes it would have poped up! Well shes fixed and running strong and back to the car I loved to drive whene I bought it so its all good and will experience farfignugen once again! "have not heard that word in a wile"


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## purevw2 (Jul 27, 2002)

*Re: location of a sensor (2000 jetta)*

Thanks for the location, brought my 2000 jetta into the vdub shop for a sensor then they tell me no you should have us run a $80 test first. Symtums) fan does not turn on to regulate temp, overheating, engine light constantly on, rpm's real high at stop signs etc., 70% driving perfection.
Can anyone help me it's urgent??????


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## 98wolfie (Jun 1, 2002)

*Re: Symptoms of a bad oxygen sensor! (1993jetta GL)*

Do you guys think I'm having the same problem? I have a 98 Jetta 2.0 w/120,000miles and the car sputters at startup, exhaust is a little smoky, and gas mileage isn't very great anymore. Do you think my O2 sensor is shot?


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## engine101 (Apr 8, 2002)

*Re: Symptoms of a bad oxygen sensor! (98wolfie)*

Although those symptoms are similar to a bad O2 sensor, it doesn't mean that's the only thing wrong. If you never replaced it them, i'd definitely get it your vw vagged and see if it's throwin codes.


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## purevw2 (Jul 27, 2002)

*Re: location of a sensor (1993jetta GL)*

doesn't it feel great to have things up and running!? hopefully we will have some good luck with replacing the sensor too! happy driving http://****************.com/smile/emthup.gif


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