I have a 1999 Nissan Sentra and the check engine light comes on and goes off constantly.

I have a 1999 Nissan Sentra and the check engine light comes on and goes off constantly.

I have a 1999 Nissan Sentra and the check engine light comes on and goes off constantly. Every time I had it checked, I get a cylinder one misfire. I have also noticed that when the air temp seems to be “just right”, the light remains off and the car runs great. But if it is too hot or cold, the light is on and the car runs very rough. I have changed the plugs, wires, cap and rotor and the ambient temperature sensor (thinking it’s an air/fuel ratio problem). Nothing works. The only other issue I can think of is a clogged injector but then why the on-again, off-again? Any ideas what the issue might be? Thanks

We replace many connector pigtails to EFI fuel injectors; check that the connector is tight and the spring lock is still there and engaging with a "click.” That type of problem could be intermittent. To check the injector itself requires an ohm meter to take a measurement between the two terminals. Resistance should be between 10 and 14 ohms. If it is outside that range, it’s probably failing, could work intermittently and will soon stop working. Replace it.

Jim O’Neill
Chino Autotech Inc.
Auto Club SoCal AAR

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