1998 Nissan Altima fails smog check after 600 miles of driving.

I took my car to get a smog check they hooked my car to the machine and told me it could not be done. He told me its not reading i need to drive about 50 more mile and come back. I had a engine diagnostic test done and they told me there was nothing wrong with the car. Drive 200 more miles and come back..all in all i have driven over 600 miles been back to the smog place about 4 times and they dont know why it wont read when hooked up to the smog check machine....can anyone help?

Answer:

What's happening here... Or rather what's not happening, is the emission monitors are not setting. The reason they are not setting has to be found. You'll need an expert smog check repair station to retrieve freeze frame data from your Nissan Altima's OBD II computer, and any other data they can gather to find out why the system is not triggering certain emission monitors to set or perhaps even run. We can only recommend you visit a smog check repair station. A test only smog check station is not going to be able to offer any assistance. They (test only centers) are not allowed to comment on any smog check failure. You will need to get a diagnosis from a smog check repair station.

posted by SmogTips Support