Rheem code 93: neutralizer replacement required

Code 93 follows code 92. Where 92 is the warning, 93 means the neutralizer is used up and the heater has stopped.

This page uses two Rheem sources: the current Rheem and Ruud tankless troubleshooting manual, and Rheem's error code list for earlier tankless models. Codes can differ between generations, so the meaning for each is shown where they differ. Rheem technical support: (800) 432-8373.

What it means by model generation

What to do

1. Replace the neutralizer with a kit from a Rheem or Ruud supplier. The media is calcium carbonate.
2. Check the condensate drain line for blockage while you are there.
3. Reset: remote on, no water running, press MIN and MAX together until CL appears, then again for more than 5 seconds until CL disappears.

Prevent it next time

Check the neutralizer at each yearly service, along with the flush and filter cleaning. A condensate drain problem, code 29 on condensing models, can also shut the heater down.

Before you call

Have the model and serial number from the rating label ready, and note whether your unit is a condensing (high-efficiency) or non-condensing model. Tell the technician the exact code, when it appears and any recent work on the gas, water, venting or electrical supply. That often saves a second visit.

See every code on our Rheem error codes page.