Hard reboot for ecu needed possibly?

1998 NISSAN ALTIMA
120,000 MILES • 2.4L • 4 CYL • 2WD • AUTOMATIC
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JESSS
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Installed used engine, changed spark plugs, wires, dist cap, rotor, air filter, fuel filter, Mass Airflow Sensor, EGR, O2 Sensor

No vacuum leaks.

Check engine light still comes on intermittently reading lean bank one.

Is there a hard reset for the ECU I should perform specific to my car to stop this so I can pass smog?
Jan 19, 2026 at 4:52 PM
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STRAILER
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Yep, you can try a hard reboot, here is a video to show you how.

https://www.youtube.com/watch?v=INiDRO5A5MY

Is there any intake or exhaust leaks, these both can cause a lean mixture, here is a guide to help.

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

This video will show you how to check for vacuum leaks.

https://www.youtube.com/watch?v=LRKWV4Are5c&pp=0gcJCYcKAYcqIYzv

Please upload a short video with the engine running in your response, so I can see what's going on. Please go over these guides and get back to us.

Jan 20, 2026 at 9:44 AM
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JESSS
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Thank you for your help. I go to my mechanic tomorrow. They checked already and said there are no vacuum leaks. I will let the look at it again and when I pick it up after they clear the codes again I will drive it like the manual says when it's new so the ECU learns correctly because I put a used like engine in it.
Jan 20, 2026 at 6:37 PM
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STRAILER
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An exhaust leak will cause this as well. When you say I replaced the fuel filter, was it the fuel filter inside the gas tank?
Jan 21, 2026 at 9:03 AM
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JESSS
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Hi,
No it was the external fuel filter that is under the hood.

Also, I watched your video and bought the little wire with alligator teeth. They sold me a set that has two separate wires one red, one black with teeth. Can I use one of those to attach to the positive and negative to drain the car like you did?
Jan 21, 2026 at 11:48 AM
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JESSS
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Mechanic is not available until tomorrow so I want to try to drain and then relearn my ICU to my cars specific pattern in the manual like you said.
Jan 21, 2026 at 11:53 AM
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JESSS
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Do you think I should wait to do that until after the mechanic has it for a day to see if they can find any exhaust leaks or anything else.
Jan 21, 2026 at 11:55 AM
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STRAILER
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Yes, I would wait until the mechanic looks at it.
Jan 23, 2026 at 8:41 AM
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JESSS
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Hi Ken,
Do you have a phone number I can call you at? I really need your expert opinion. I just picked my car up from the mechanic and wanted to go over what he thinks. My number is 805-276-6834
Jan 28, 2026 at 12:03 PM
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STRAILER
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We cant make calls, can you explain here what is going on?
Jan 29, 2026 at 8:53 AM