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Rheem 45: Low pressure switch open with inducer on high speed

Ref. RHEEM-45 · From the Rheem furnace manual · Updated 2026-10-23

Status code45Rheem
What it means

Low pressure switch open with inducer on high speed.

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How it shows: Dual 7-segment display: 45

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§1Likely causes

  • Blocked or improperly terminated inlet/exhaust vents
  • Vent length or elbows exceed maximum
  • Faulty or disconnected inducer
  • Faulty control board (inducer relay)
  • Loose or faulty wiring
  • Disconnected, blocked, split or cut pressure switch hoses
  • Wind gusts
  • Faulty pressure switch

§2Safe DIY steps

  1. Check outdoor vent terminations for blockage
  2. Techniciancheck venting, inducer, hoses, wiring and pressure switch
Safety firstIf you smell gas, do not touch any electrical switch or use a phone in the building; leave immediately and call your gas supplier from outside. Turn off electrical power at the furnace switch or breaker before opening any panel, and never bypass or jumper a limit, rollout or pressure switch. Gas valve, burner, venting, wiring and control-board work should be done by a licensed HVAC technician.

§3When to call a pro

Call a licensed HVAC technician: if vents are clear and the code persists.

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§4Other Rheem codes

10Rheem

One-hour lockout, caused by repeated failed ignition (11), water sensed (59), dead blower (61), internal fault (93), flame lost 5 times (13) or unexpected flame (14).

11Rheem

Failed ignition. After four failed attempts the control enters one-hour lockout (10).

12Rheem

Low flame sense: flame sense current is weak or marginal. Furnace keeps running.

13Rheem

Flame lost after established.

14Rheem

Flame present with gas valve off. Extremely critical; furnace will not operate.

30Rheem

Open fuse, usually from a 24 VAC short to common or ground.