Codes 420 and 755

Hello all, I have a 1996 camry le with 197k on it i recently got a cel and had it scanned. came up with codes 420 and 755. Can anyone tell me what I should look for to fix this problem ? thanks

For a generaic definition of the codes use this site:

http://www.iequus.com/support/obd2_definitions.php

Also, the Toyota factory service manuals stickied at the top of this forum's home page will have the troubleshooting charts for each of the codes. Download the generation 4 manual. Here's the link to the manuals:

http://www.automotiveforums.com/vbulletin/showthread.php?t=497839

Mike

First, delete the codes and see if they reappear. I have had the P0420 code go away and not return after I deleted the code. Same may be true of the P0775 code.

P0420 Catalyst System Efficiency Below Threshold (Bank 1)
1. Check for leaks in the exhaust system between the engine and the cat converter (loose connection, rusted area, or burned out seal)

2. HO2 or A/F ratio sensor before cat converter is bad (remove connector and measure resistance between terminals +B and HT - should be 0.8-1.4 ohms cold).

3. HO2 sensor after cat converter is bad (measure resistance as above - should be 11-16 ohms cold). <= Most likely

4. Cat converter is bad.

If you need to replace a sensor, bring your VIN to a Toyota dealer and get the correct part number for your engine. There is only one that works correctly, but at least two available. You don't have to buy the part from Toyota, but you have to have the correct part number.

P0755 Shift Solenoid B Malfunction
Replacing the fluid in the transmission may help, otherwise you have to replace solenoid B.

If you have the 4-cylinder, definitely check the exhaust header to downpipe connection as suggested by Brian. Leaks here are usually audible. I find those nuts to always be either loose or missing due to the inherent vibrations of the 4-cyl. Loctite helps. The colder weather exacerbates the vibration due to colder rubber in the engine mounts.

Great info ! thanks guys.