What Those Blinking Lights on Your Pool Equipment Mean

Pool equipment is a world of its own. The control panels look like they were designed by engineers who have never met a regular human. Blinking lights, two-letter codes, and cryptic abbreviations everywhere.

Here's the cheat sheet you actually need.

Pool Heater Codes

IF / Ignition Failure

Your heater tried to light and couldn't. Usually means: dirty igniter, no gas supply, or clogged burner orifices. First check: make sure the gas is on. Second check: clean the igniter with fine sandpaper and try again. Third: check for spider webs in the burner tray — yes, really. Spiders love pool heater burner tubes. (Hayward IF diagnosis · Jandy IGN FAIL diagnosis · Pentair E01 diagnosis)

HI / High Limit

Water temperature exceeded the safety limit. This is either a stuck-on gas valve (rare) or a flow restriction. Most common cause: dirty pool filter. When water flow drops, the water inside the heater sits too long and overheats. Clean or backwash your filter.

LO / Low Water Flow

There isn't enough water moving through the heater. Check: is the pump running? Is the filter dirty? Are any valves partially closed? Is the skimmer basket full of leaves? (Hayward LO diagnosis · Pentair E05 diagnosis)

Variable Speed Pump Codes

OC / Overcurrent

The motor is drawing too much power. Usually means something is jamming the impeller or the motor bearings are going bad. Turn off the pump, check the strainer basket and impeller for debris. (Hayward E01 diagnosis · Pentair E06 diagnosis)

PF / Power Failure

The pump lost power and is telling you about it. Often happens after a brief power flicker. Press the Start button to restart. If it keeps happening, check the circuit breaker and wiring connections.

Salt Chlorinator Codes

Low Salt / Check Salt

The salt level is below the minimum (usually 2,700 PPM). Add salt. Use a proper salt test (not just the chlorinator's reading, which can drift). Pool stores will test for free. (Hayward CHECK SALT diagnosis · Pentair LOW SALT diagnosis)

High Salt

Salt is above the maximum (usually 4,500 PPM). There's no quick fix for this — you have to partially drain and refill with fresh water to dilute it. This is why you add salt gradually.

Inspect Cell / Clean Cell

Calcium has built up on the cell plates. Remove the cell, soak it in a 4:1 water-to-acid solution for 15 minutes, rinse, and reinstall. Do this every 3-6 months depending on your calcium hardness level.

When to Call a Pool Pro

Most pool equipment codes are flow or chemical related — things you can handle. Call a pro for: gas leaks (you'll smell it), electrical faults, strange burning smells, or refrigerant issues on heat pumps.