iRule to mark pool member down if HTTP Status Code 502/503

I'd suggest that using a HTTP health monitor would be more appropriate. In this case perhaps a second monitor configured for 'reverse' mode so the Pool Member is marked up unless a 502 is received; you can configure it to mark down after 5 occurances using the appropriate timer values. Then you'd just need to add the monitor to the Pool and configure it to mark down if either monitor fails.

Thank you, let me try both and easiest one I will pick it. Thanks for guidelines. I will update you the results.