Heated Oxygen Sensor?

[porkfriedrice]

Hi there. I have a 97 Corolla that has a P0130 code showing. So I got out the Haynes manual and read up on the O2 sensor. According to Haynes on page 6-11, it states that all models after 1996 have heated O2 sensors. On page 6-13, it says that models with heated sensors will have a four-wire connector. The connector on mine only has two wires. So is the manual wrong about post-96 models having heated sensors? Or am I missing something here?

Also sort of related, I did the test for sensor voltage at the black wire as the manual says. The volts only fluctuated between .300 and .600 or so, not .100 to .900. Is this enough to assume that the sensor is bad and is the reason for the code? Or should I try other things before assuming it's bad. Thank you all for helping me with my crappy troubleshooting skills.

[Kiwi-Corolla]

Originally Posted by porkfriedrice

Hi there. I have a 97 Corolla that has a P0130 code showing. So I got out the Haynes manual and read up on the O2 sensor. According to Haynes on page 6-11, it states that all models after 1996 have heated O2 sensors. On page 6-13, it says that models with heated sensors will have a four-wire connector. The connector on mine only has two wires. So is the manual wrong about post-96 models having heated sensors? Or am I missing something here?

Welcome to the forums! Yes, a heated oxygen sensor should have four wires. My non-heated oxygen sensor only has one wire, but I've seen photos of Geo Prizms that have two wires . Not quite sure about that one.

Originally Posted by porkfriedrice

Also sort of related, I did the test for sensor voltage at the black wire as the manual says. The volts only fluctuated between .300 and .600 or so, not .100 to .900. Is this enough to assume that the sensor is bad and is the reason for the code? Or should I try other things before assuming it's bad. Thank you all for helping me with my crappy troubleshooting skills.

What the Haynes manual failed to mention is that you're meant to increase the engine speed to 4,000 rpm when checking the oxygen sensor with a digital multimeter. Try that and see if it makes a difference. I checked mine recently and it didn't display the correct reading until I increased the engine speed. This was listed as one of the instructions in my Gregory's Corolla repair manual, whereas in my Haynes manual it was not.

[porkfriedrice]

Thanks for the reply. I guess I shouldn't put all my faith in the Haynes being accurate. Does the forum have any troubleshooting articles that are code-specific? I looked around the site a bit, but didn't see anything. I don't want to just replace the O2 sensor if that's not what the problem is.

[Kiwi-Corolla]

Originally Posted by porkfriedrice

Thanks for the reply. I guess I shouldn't put all my faith in the Haynes being accurate. Does the forum have any troubleshooting articles that are code-specific? I looked around the site a bit, but didn't see anything. I don't want to just replace the O2 sensor if that's not what the problem is.

No problem . Are you experiencing any problems/symptoms aside from the check engine light on the dash? (such as higher fuel consumption, lack of engine power etc). I'd be inclined to test the oxygen sensor again. If the reading still doesn't fluctuate between 0.1-0.9 volts, replace it with a new one.

If you're using the search feature on the forums, I'd highly recommend searching for one word at a time as it's a lot more accurate. So for example, instead of searching for "oxygen sensor", simply search for "oxygen", and change the option in the drop-down box to 'Search Titles Only'. I can't recall any threads being OBD-II code-specific, but there's a lot of information here so something is bound to come up. Good luck and happy holidays!

[porkfriedrice]

There hasn't been any drive-ability issues that I've noticed. For the last few months I have noticed a slight gas smell upon startup. I have read that this may be indicative of a bad O2 sensor, as the mixture is too lean. I will try to do more searches to point me in the right direction. Don't want to be one of those who don't bother to search first! Thank you and happy holiday!

[Kiwi-Corolla]

Originally Posted by porkfriedrice

There hasn't been any drive-ability issues that I've noticed. For the last few months I have noticed a slight gas smell upon startup. I have read that this may be indicative of a bad O2 sensor, as the mixture is too lean. I will try to do more searches to point me in the right direction. Don't want to be one of those who don't bother to search first! Thank you and happy holiday!

Ok cool. Is the smell coming from the tail pipe or from the engine bay? It could be a sign that the charcoal canister needs replacing.

When checking your oxygen sensor with a multimeter, if the reading does not rise above 0.7 volts, a lean mixture is indicated. Common causes of a lean mixture are due to low fuel pressure, vacuum leaks, blocked or faulty injectors, MAP sensor or the ignition system.

However, if the reading does not fall below 0.35 volts, a rich mixture is indicated. Common causes of a rich mixture are due to high fuel pressure, coolant temperature sensor, leaking injectors, MAP sensor, intake air temperature sensor or the throttle position sensor.

Best of luck with your search. I hope you come across something useful

[porkfriedrice]

The smell is apparent inside the car after first startup. It seems like a mixture of exhaust/gas. So I guess the answer is tailpipe? So the P0130 could be any of the issues you described if the multimeter readings aren't correct? Or should I still replace that O2 sensor? Don't worry, I still plan on searching for threads here, but I've had a few beers and I won't be able to process everything

[speedy25]

I have found that a good wire brushing to remove deposits from O2 sensors usually revives them enough to stop codes from popping up.

-SP