Rheem · Furnace

12 Low flame sense

Medium severity Rheem/Ruud 802P / 80MDP 80% two-stage furnace (UT 1028-928 IFC)R95PRGPE/RGLE

What the control is telling you

Flame is present but the signal is weak; the furnace usually keeps running. On 802P/R95P the amber flame LED blinks slowly (1-4 times per second).

Applies to: 802P/80MDP (802PA050-150); R95P (R95PA040-115); RGPE/RGLE 2-stage 80+

Likely causes

Dirty or oxidized flame sensor
Poor ground
L1/neutral reversed
Flame not fully contacting the sensor / carry-over issue
R95P: twinned units with transformers out of phase (flame LED dim)

Test and repair steps

Clean the flame sensor rod - recommended at the start of each heating season.
Check flame sensor wire continuity to the IFC (RGPE/RGLE: J1 pin 1).
Check IFC and furnace grounding.
Verify L1/neutral polarity.
Check gas pressure and that flame carries across all burners.
R95P on twinned units confirm both transformers are in phase.

Settings for these units

Clearance to combustibles (all models) · R95P
Filter sizes as shipped, upflow (Table 19) · RGPE/RGLE
Reduced clearance to combustibles, upflow/horizontal (Fig. 4) · Rheem/Ruud 802P / 80MDP 80% two-stage furnace (UT 1028-928 IFC)
Reduced clearance to combustibles (Fig. 3 and 4) · RGPE/RGLE

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Source: 802P: 92-24161-146-02, Diagnostics and Fault Codes table, p.40, 43, 51; R95P: Diagnostics and Fault Codes table, p.87 (PDF p.91); RGPE/RGLE: Table 16 p.49 / Table 20; Fig. 45 p.63. Summarized in our own words; check the original manual for your model.

Homeowner looking at this code? See what it means for you and when to call a technician.

For licensed technicians. Gas, electrical and refrigerant work must be done by a qualified, licensed person. Shut off power and gas before servicing, never bypass a safety control, and follow the manufacturer’s manual for the exact model; it and local codes always take priority. HVACopedia is not affiliated with any manufacturer; brand and model names only identify the equipment.