Beckett Burner locking out after initial flame

NJBoater

Hello,

Just wondering if someone has an idea of what my problem is. The burner will ignite with a good flame and run for the 20 seconds and then lock out. I have tried to reset and it does the exact same thing after the 20 seconds.

I was thinking the cad cell, which I plan on picking one up today but also think it might be the cad cell relay. My thoughts on that is because I thought (and I could be wrong) that if I started the boiler and then jumped the F-F terminals that it bypasses the cad cell eye and would keep the flame going but it did not. This makes me think the cad cell relay is bad.

I have already cleaned the filter and replaced the nozzle and checked the electrodes.

Thanks for any help!