Will a bad o2 sensor lead to a 'check engine' light or some kind of warning?

[BobLoblaw]

Topic. I only want to replace it if I have to. So far I have no 'check engine' light coming on in my 94 Pathy XE.

[Simon]

Topic. I only want to replace it if I have to. So far I have no 'check engine' light coming on in my 94 Pathy XE.

 

Not always. Run the ECU codes (search the forum for instructions). It may show up there, even if you don't have a CEL triggered.

[94extreme]

what simon said.. sometimes it will not trigger the light.. also, the light could be burnt.

[GhostPath]

Not only will a bad O2 sensor sometimes not set a check engine light, many of the WD21s don't even *have* a check engine light.

Edited February 7, 2008 by GhostPath

[BobLoblaw]

Would you guys recommend a Bosch or a NTK o2 sensor? Bosch is $20 cheaper if that helps you decide.

[GhostPath]

Either will work fine, but the NTK *is* OEM.