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9

Rheem Water Heater

Severity: Moderate

Source: OnlyErrorCodes.com — Every error code. One place.

Rheem Water Heater Error 9 — Igniter Wiring Fault Fix

What Does This Error Mean?

Error 9 indicates an igniter problem — either the igniter itself isn't firing, or the flame sensor isn't seeing flame after a successful ignition attempt.
This is usually a wiring or sensor issue rather than gas supply.
Most homeowners can't fix Error 9 themselves.
Power-cycle the unit once; if it returns, call a licensed gas service technician.

Affected Models

  • Rheem RTGH series
  • Rheem RTG-95
  • Rheem RTGH-95DVLN
  • Rheem Performance Platinum tankless

Common Causes

  • Igniter wire loose at the control board connector
  • Flame sensor coated with carbon (false 'no flame' reading)
  • Igniter element worn out (after 5+ years of use)
  • Damaged wiring inside the unit (rodent or vibration)
  • Control board fault sending no ignition command

How to Fix It

  1. Power-cycle the heater first.

    Press the on/off button.
    Wait 60 seconds.
    Power back on.
    Run hot water to test.
    Sometimes a one-off Error 9 (a single failed ignition attempt) clears on the next start.
    If it persists, treat it as a real fault.

  2. Listen for the ignition click.

    When you turn on hot water, the unit should click 3–5 times as it tries to light.
    If you hear no clicks, the igniter isn't firing — control board issue.
    If you hear clicks but no flame, the gas valve or sensor is the issue.

  3. Check the gas supply.

    Make sure the gas valve at the unit is in the on position (handle parallel to the pipe).
    Test another gas appliance (stove, dryer) to confirm gas is flowing to the house.
    If other gas appliances work, the supply is fine — the fault is at the heater.

  4. Don't open the unit yourself.

    The flame sensor and igniter are inside the combustion chamber.
    Working in there means handling gas-control components and potentially live electricity.
    This is a licensed-installer-only repair.
    Don't try to access the igniter to clean it — risk of leak and CO is real.

  5. Call a licensed installer.

    If Error 9 returns after a power cycle, schedule service.
    Have your model number and serial number ready when you call.
    The tech will check the flame sensor first (most common), then the igniter, then the wiring.
    Most repairs are under 200 USD parts plus labor.

Frequently Asked Questions

Can a dirty flame sensor cause Error 9?

Yes — over years, the flame sensor accumulates a thin carbon coating that insulates it from sensing the actual flame.
The igniter fires, gas flows, flame appears, but the sensor doesn't 'see' it and the unit shuts off thinking the ignition failed.
A tech cleans this with fine emery cloth in 10 minutes.

How long does an igniter last?

5–8 years for typical residential use.
Hard-water areas or units that cycle frequently (large families) wear them out faster.
Replacement igniters are 30–60 USD parts, plus labor.
If your unit is past 8 years and Error 9 has returned, replace the igniter as preventative.