Pump shows E12 sensor error; temperature or flow readings on the display are clearly incorrect.

Safety First: Turn OFF power before disconnecting any sensors.

• Identify the faulty sensor: Compare displayed temperature/pressure/flow to actual conditions. The sensor with unrealistic readings is likely at fault.
• Inspect sensor wiring: Trace the sensor cable from the probe to the Rheem control board. Look for cuts, abrasions, or rodent damage. Repair or replace as needed.
• Check connections: Unplug the sensor connector at the control, inspect for corrosion or bent pins, clean with contact cleaner, and reconnect firmly.
• Measure sensor resistance: Using a multimeter, measure resistance of the temperature sensor and compare to Rheem's resistance vs. temperature chart. Replace if out of range.
• Replace sensor: If wiring and connections are good but E12 persists, replace the affected Rheem sensor with an OEM part and clear the error by cycling power.