My miller home furnace MMHA-077ABHR-02 has a UT Electronic Controls 1018 series hot surface ignitor that is repeatedly flashing 3 times. Furnace goes through the cycle for starting, solonoid for gas opens momentarily and shuts right back off, and furnace will not light.

First look at this flow chart

Mobile Home Repair - Mobile Home Gas Furnace Operation Flow Chart

Next. You might try and cleaning the flame rod with steel wool.
If all else fails call for service.

I got a miller furnace I light the pilot and when the burner lights I hear a puffing sound the pilot light mite stay on 1min 1 hr or 1 day but it goes out it's a down flow I got it going blowing up its on a 9in box then its L up to a 14in box to 3 vent 4in stove pipe 8in around that for clean air the clean air pipe goes about 3ft to a new room the furnace is in a 3 by 5 room the 4in stove pipe starts in the basement at the hot water hearer goes up to first floor that's were the furnace then to the roof about 8ft over the roof with a cap pilot light looks good blue flam with a yellow tip

On the other side of your burners is a flame sensor take it our and clean it with some emory or light sand paper wipe it off good and replace it.. the unit should work fine after that . If its not reading the flame is auto shuts off after about 3 to 5 seconds..