How to Fix / Troubleshooting

Safety first: Turn off power before removing panels or touching wiring.

Step 1 – Locate return sensor: Find the return temperature sensor on the boiler’s return pipe. It will look similar to the flow sensor.
Step 2 – Inspect and reseat: Check the sensor body and wiring for damage. Reseat the connector at the sensor and on the main PCB.
Step 3 – Check for leaks: Inspect nearby pipe joints and fittings for leaks that could wet the sensor. Repair leaks and dry components.
Step 4 – Test sensor: Disconnect the sensor and measure resistance. Compare to Rheem’s chart. Replace the sensor if readings are out of specification.
Step 5 – Harness check: If the sensor is good, inspect the harness for continuity and shorts. Replace if damaged.

Warning: Incorrect return temperature readings can cause short cycling and stress on the boiler. Address sensor faults promptly.

Boiler shows E11 and may cycle erratically, temperature readings appear incorrect

Possible Causes