A loose gas cap is one common reason.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's
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Jude, I had this happen to me, I had a faulty connection to the oil
pressure sender switch on the engine, it also showed low or no oil
pressure on the gauge. I rewired the connector and everything is fine.
It may be worth a look.

How many miles?  Could be an O2 sensor.

A quick look at quadratecs sight and I found this page.

http://www.quadratec.com/cgi-bin/sgdynamo.exe?HTNAME=tech_corner.html&checked=Y

from what it states that if you

To check your YJ/TJ Codes, use this sequence on your ignition.
On-Off-On-Off-On and then begin to count the flashes from the check
engine light.

on my 97 tj the odometer displayed the codes they end with a "53"
I noticed the link to quadratec has the codes for you there.
hope this helps.

Mike S.