Difference O2 sensor readings before and after cats?
Thread Starter
Melting Slicks
Joined: Feb 2001
Posts: 2,137
Likes: 1
From: Oklahoma City OK
Cruise-In III Veteran
Difference in O2 sensor readings before and after cats?
Does the exhaust going through the cats make much of a difference on the O2 readings? Does it add or subtract from the "real" O2 numbers? Most of the dyno shops use a tailpipe sniffer. How does that compare with using the sensor in front of the cats?
[Modified by FRISKY, 9:19 PM 5/6/2002]
[Modified by FRISKY, 9:19 PM 5/6/2002]
Melting Slicks
Joined: Mar 2001
Posts: 2,668
Likes: 849
From: New Jersey
Re: Difference in O2 sensor readings before and after cats? (FRISKY)
The OBD2 computer looks at the difference between the pre and post OX sensors to determine if the cat is working. The signals are normally different if the cat is chemically "working". Removing the cats and retaining the 2 OX sensors will cause a check engine light.
Thread Starter
Melting Slicks
Joined: Feb 2001
Posts: 2,137
Likes: 1
From: Oklahoma City OK
Cruise-In III Veteran
Re: Difference in O2 sensor readings before and after cats?
Thanks for the answers guys but I'm not asking this because I want to remove the cats.
What I really want to know is the tailpipe O2 "sniffer" from the dyno shop giving me the same O2 readings as a sniffer put in the pipe before the cats? In other words, how accurate is a tailpipe sniffer?
What I really want to know is the tailpipe O2 "sniffer" from the dyno shop giving me the same O2 readings as a sniffer put in the pipe before the cats? In other words, how accurate is a tailpipe sniffer?
