Zodiac pool heater shows E16; may be associated with low-voltage or power issues.

Safety: Turn off power at the breaker before opening the electrical junction box. Only work on line voltage if you are qualified.

• Inspect power connections: Verify that all line and neutral connections at the heater's terminal block are tight and free of corrosion or heat damage.
• Check wire size and length: Compare installed wire gauge and run length to Zodiac installation requirements. Undersized wire can cause voltage drop.
• Measure voltage: With power on and using a multimeter, measure line voltage at the heater while the unit is attempting to run. Voltage should be within the specified range (typically ±10% of nominal).
• Check transformer output: If equipped with a low-voltage transformer, measure its secondary output. A weak or failed transformer can cause control issues.
• Correct supply issues: Tighten connections, replace damaged wiring, or have an electrician correct panel or supply problems. Replace the transformer with a Zodiac-compatible unit if defective.