Is it possible to enter the US through the Nexus lane while my Nexus card is being renewed? And how?
According to the CBP website, you can use an Expired NEXUS card, provided you have submitted your renewal, for up to 6 or 12 months after expiry. The grace period is normally 6 months, but as of December 2019 CBP has extended it to 12 months.
If you submitted a renewal application before expiration of your current membership, then you can continue to use your benefits until the renewal is finalized (up to 6 months after your expiration date). CBP "I have submitted my Trusted Traveler application for review. Did CBP receive my application?"
As of December 2019, the Dashboard of the Trusted Traveler Program website says,
Due to a significant increase in application volume, we are extending the grace period from 6 months to 1 year for any submitted renewal application. This means you will continue to receive full benefits for 1 year while U.S. Customs and Border Protection is finalizing your renewal application.…
This note then links to a popup document How do I renew my Trusted Traveler (Global Entry, NEXUS, SENTRI or FAST) membership?, without a clear URL. This popup document says,
…If you submit a renewal application before your membership expires, you will be able to continue to use benefits up to 1 year after your membership expiration date.…
You can use your NEXUS card for up to 6 months past the expiration date just as Jason said. So long as you submitted your renewal application before it expired. Here is the link that gives you that information. https://help.cbp.gov/app/answers/detail/a_id/1332/~/i-have-submitted-my-trusted-traveler-application-for-review.-did-cbp-receive-my
The links above no longer work - here is the new link https://help.cbp.gov/s/article/Article-1332?language=en_US - note that the article calls out that you an use your card for up to 6 months if you apply to renew it before it expires.