My engine light has been on for about 2 weeks. I brought it in to have it checked out and get a smog check. I was told the pressure sensor for the fuel tank needs to be replaced; and it will not pass smog in California without this repair costing just under $400.00. Does this sound about right? My car seems to be running fine.
Filling up with the engine running, or a dirty/ bad gas cap can also cause this. One car we had had a pump that pressurized the system for the test and the pump failed. Try cleaning the contact areas of the gas cap and filler neck, worked for me once, it may take 50 miles or so until the light goes off. Best off finding someone who can diagnose the problem before throwing parts in.
Please give us a year for this Miata. If you have the DTC code from the code reader, supply that. With the code and its exact wording, we should be able to ascertain if you need a new pressure monitor. It is possible that the problem is something other than the sensor itself, i.e. power supply, plumbing, solenoid switch valve, etc.
You are not going to be able to pass the CA smog check with a lite CEL. Probably the evaporative system monitor will not be complete as well so you might have to drive the Miata long enough to complete that monitor.
Get back to us with the relevant information and we can advise you further.