OT:Can the O2 sensor be bad even if there is no fault code?

[Hallmark]

I have a '96 Mazda B2300. It passes the emissions for state inspection, but the check engine light is on (has been for almost a year) so I can't get a new inspection sticker. The inspection station says there are no fault codes for any of the components the system moniters. My indy says the only diagnostic he gets is that it's running lean. I've run fuel injector cleaner through it, checked for vacuum leaks, and done routine items like change the air filter and oil.

My indy says the O2 sensors (the thing has two) could be bad even with no fault code showing. Is this true? I'm trying to decide if I should order two new O2 sensors (ouch $) just to see if this will clear the display so I can get an inspection sticker.

[Bill R.]

come back on? Its obdII so it should give you a specific code number.
You probably have a slight hesitation also...









I have a '96 Mazda B2300. It passes the emissions for state inspection, but the check engine light is on (has been for almost a year) so I can't get a new inspection sticker. The inspection station says there are no fault codes for any of the components the system moniters. My indy says the only diagnostic he gets is that it's running lean. I've run fuel injector cleaner through it, checked for vacuum leaks, and done routine items like change the air filter and oil.

My indy says the O2 sensors (the thing has two) could be bad even with no fault code showing. Is this true? I'm trying to decide if I should order two new O2 sensors (ouch $) just to see if this will clear the display so I can get an inspection sticker.

[Hallmark]

I haven't noticed any hesitation, but it does seem to be underpowered.

Oddly enough, my daughter was driving the truck back from the indy and someone pulled out in front of her in traffic. She honked the horn at the guy and the check engine light came back on. I reset it again by disconnecting the battery and it stayed off less than 15 minutes.