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Error code reference
Rheem Water Heater Error Code P1
Not enough water flow to operate the unit.
SourceRheem Tankless Water Heater - Use & Care Manual with Installation Instructionsp. 25, 26
Diagnostic procedure
The full P1 procedure
Step 1 is visible so you can confirm you are on the right page. The remaining steps, the ones that tell you whether to actually replace a part, unlock with any pass.
MyPros+ · DiagnosticsStep 1 preview
1
First diagnostic step
Increase the water flow from the fixtures.
SourceRheem Tankless Water Heater - Use & Care Manual with Installation Instructionsp. 25, 26
More steps, wiring diagram references, and verified part numbers
Includes expected resistance and voltage values, connector pinouts, and supersession notes for replacement parts.
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Where this code is documented
1 manual in the MyPros+ library documents this code for Rheem water heater.
Models covered by the manuals that document this code
75,000+ service documents · 20,000+ error codes · 100+ brands
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