1991 Camry v6

[JimmyJammy]

I recently purchased a 91 camry it has right at 100,000 miles on it and seemed to be running great but recently the check engine light came on i came up with codes 25 and 26 which are air to fuel ratio lean and rich malfunction. From what i have read it appears that there are many diffrent things that could be causing this problem from o2 sensor to injector circuit problems. Has anyone had a similar problem as this or any ideas where i should start i talked to a mechanic he said could cost $300 to fix depending on what they have to troubleshoot. I really dont want to spend alot of money on this car because i am planning on selling very soon because I got a great deal on another vehicle but i am worried that i will have problems selling with check engine light on. I also recently noticed that it will run hot if i ride with a/c on but when i turn it off it runs normal. Any ideas on where i could start would be greatly appreciated i just wanna be able to sell this car to pay off another.
thanks for any help

[toyrolla]

I would change the O2 sensor for starters.
A common symptom when the O2 sensor fails is that the car runs rich (too much fuel).
The ECU gets bad readings from the faulty sensor and as a result, alters the fuel map by dumping more fuel than it should.

From my past experience, I'd go with a sensor from the dealer.
After you install it, reset the ECU by either disconnecting the neg cable from the battery or else unplug the EFI fuse and wait at least 30 second before replugging back in (engine compartment).

This will reset the ECU and allow it to take new readings from the new sensor.

Also if the air filter is dirty, I would replace that too.

After approx 5-10 miles of driving, check for codes and see what you have.

This is a DIY type of task, so you won't need to spend $300 at a mechanic.

Good luck...

[JimmyJammy]

It appears that there are 2 o2 sensors should i replace both? They are pretty exspensive i found the oe style on partswarehouse for $100 and $78 i would hate to replace both and only one be bad.
Thanks for the help!

[toyomoho]

Might also be injector circuit, airflow meter, water temp sensor. Does the A/C radiator fan turn on when the A/C compressor is working?

The manual states to only be concerned with sub 02 sensor if Code 27 is present.

[JimmyJammy]

How would i go about narrowing down what is causing the problem? I will check the ac fan tomorrow and reply back

[JimmyJammy]

There are 2 fans in front of the radiator and they are both running constantly i am assuming these are the fans you are asking about. I let car run for a few min both fans ran all the time with ac on or off.
Thanks!

[toyrolla]

Originally Posted by JimmyJammy

It appears that there are 2 o2 sensors should i replace both? They are pretty exspensive i found the oe style on partswarehouse for $100 and $78 i would hate to replace both and only one be bad.
Thanks for the help!

For that cost, you can get actual Denso (Nippondenso) OEM replacements:

http://www.densoproducts.com

2-wire is $98.17
4-wire is $68.25

[JimmyJammy]

I would hate to replace the o2 sensor and that not fix the problem. Is there any way to troubleshoot them and see if they are operable or not?
Thanks for the help!