The busy link between Riverside and San Diego counties has been shut down near the I-15 split since last Wednesday.
Crews are digging a trench to replace a drainage pipe that's believed to have triggered the problem.
Caltrans had hoped to have the entire road reopened by Monday morning's rush hour, but they now say the new asphalt needs more time to harden.
MORE LOCAL HEADLINES FROM INLAND EMPIRE
USEFUL LINKS:
SEND TIP || REPORT TYPO || TWEET @abc7 || WIDGET