2000 Nissan Altima Check Engine In Town not Highway

Check engine light comes on only when I drive around the city. After 10-15 minutes on the highway, the light extinguishes.

I had the codes checked at one point and it was something to do with emissions and bank 2. If I remember, it was either the catalytic converter or the downstream O2 sensor.


Get the code(s) read again, and post the actual code(s). If your recollection is accurate, then the downstream sensor is either bad, or readings indicate a bad catalytic converter. But, if you can post the code, we can help you determine the best way to fix this.

However, it sounds like either the sensor or the cat is at the brink of failing. But, if you do not require emissions testing in you location, you can wait until which every part fails totally, and becomes easy to diagnose. Unless the cat gets plugged or blocked up, it will not hurt the engine.

Note Some auto parts stores will read the codes for free. Bring the actual codes (like P0123) not someone’s English translation.

Took a while for the light to come back on, but it did. Got it checked at Autozone for free.


It seems I need to see what O2 sensor it is and I’ve been travelling too much to get that kind of equipment hooked up. Also, it was mentioned that it could VERY easily be a dirty or loose connection.

Does that pass the common sense test for you guys? Thanks again…