Oxygen sensor or Air Fuel ratio sensor.

[stephenj37826]

Does the crz have an oxygen sensor or an air fuel ratio sensor? I've read that some new cars use a different sensor instead of o2 sensor I could be wrong though lol.

[northbridge]

the CRZ has an o2 sensor by the primary cat and one right before the secondary cat.

[RedefinedCRZ]

I would say 99% of everything 1995 and newer has 2 oxygen sensors to measure air fuel ratio (unburnt fuel). In all my years as a tech / parts manager I have yet to come across one that did not, but that is not to say there is a new car out there without one.

Sometimes people get the MAF or MAP sensor messed up with an Oxygen Sensor, terminology wise. They don't understand that the O2 sensor is in the exhaust for some reason. But northbridge is right on point, there is one up by the "manifold" if you want to call it that, and there is one before the second cat, in that pipe.

[lldsandsll]

i assumed he was confusing the o2's with the MAF

[SFLA-Z]

The service manual describes an AF Ratio sensor on the exhaust side just ahead of the 'warm-up cat-converter, and an O^2 sensor downstream of the under-floor 3-way cat. The AF Ratio wide-band sensor feedbacks to the ECM to control the air-to-fuel mix at precisely 14.7:1; the reason for the downstream O^2 sensor is explained in the manual as a comparison data measurement 'to determine catalyst efficiency'; the O^2 sensor must be more than its namesake since O^2 sensors normally has two values: rich or lean versus an AF Ratio sensor which can actually detemine the fuel ratio, and apparantly some measure of efficiency is computed. In theory, if the AF Ratio sensor in tandem with the ECM and fuel-pulse delivery is fast enough and is working, the two catalytic converters and downstream O^2 sensor is just a back-up system doing nothing.