6 Flame not proved during ignition trial

What the control is telling you

No flame was sensed during the trial for ignition. The control tries up to 3 more times, then goes to 6+1. If flame is lost during the blower-on delay the blower runs through its off delay.

Applies to: KeepRite (F/G)9MXE single-stage and (F/G)9MXT two-stage 95% furnaces

Likely causes

• Gas turned off at the valve switch or manual shut-off
• Igniter not glowing (open igniter, harness, or no 115 V from board)
• No 24 V to the gas valve
• Flame sensor dirty or grounded
• Green/yellow ground wire not on the sheet metal
• Low inlet gas pressure, poor carryover or wrong firing rate

Test and repair steps

1. Make sure the gas valve switch is ON and the manual shut-off is open.
2. Check the green/yellow ground wire is fastened to the furnace metal and the sensor is not shorted to ground.
3. Run the component test (R wire off) the igniter should glow by the end of the 15 s warm-up. If not, check 115 V at the P2 HSI connector to neutral; with voltage, check harness and igniter; without, replace the control.
4. With R back on and a heat call, confirm 24 V at the gas valve; none means check connections or the control.
5. If the valve gets 24 V but no gas flows, replace the valve.
6. If burners light then drop out, read flame current during ignition: below 0.5 microamps DC, clean the sensor with fine steel wool (normal 4.0-6.0 microamps DC); still low, replace the sensor.
7. If flame current is normal but burners still drop out, replace the control. 9MXT: also repeat in high heat; if it holds on high but not low, check low-fire manifold pressure, carryover and sensor position.

Settings for these units

• Filter size by casing width · KeepRite (F/G)96VTN Two-Stage Variable-Speed Furnace

Models that show this code

16 models in KeepRite (F/G)9MXE Single-Stage Furnace, KeepRite (F/G)9MXT Two-Stage Furnace

Other codes on the same units

• 2 Pressure switch stuck closed (did not open)
• 3 Pressure switch did not close or reopened
• 4 Limit or rollout circuit open
• 5 Flame sensed with gas valve off
• 6+1 Ignition lockout after 4 failed tries
• 7 Limit circuit lockout
• 8 Gas heating lockout - manual reset needed
• 9 High-heat pressure switch or relay did not close or reopened