What do Rheem tankless water heater error codes mean?

This chart follows the Service Error Code Chart in Rheem's condensing tankless manual, which covers its 199,900, 180,000 and 157,000 Btu/hr models. Other Rheem tankless lines, including older models, can use different codes, so check the manual for your model.

Rheem adds a notice: if the code on your display is not on the chart, turn the water heater off right away and call for service.

Start with the gas smell rule, because two of the top codes involve gas. If you smell gas, do not light anything, do not touch a switch or use a phone inside, and leave. Southwest Gas takes emergency calls at 877-860-6020, and 911 works for any suspected leak.

With no smell, here are the codes where Rheem gives an owner step:

• A011. Rheem's chart says the gas shutoff valve is not fully open. Open it completely.
• A012. Two causes. If gas service was interrupted, the chart sends you to your gas utility. If you have a propane model, check the tank and refill or swap the container.
• A090. The chart's first line is to remove any blockage at the air intake or vent opening, and it notes the air intake needs 12 inches of clearance. Look outside at the termination for leaves, a nest or stored items. The other two causes on that line, a poorly connected vent pipe and a blocked termination or inlet air filter, are a technician's.
• T113. Not enough hot water flow. Rheem's fix is to increase the water flow from the fixtures. A trickle from a low flow faucet may not be enough to fire the heater.

Everything else on the chart says to contact a dealer or a qualified service technician. Rheem's manual is direct that owners should not attempt repair of electrical wiring, gas piping, the heater control, burners, vent connectors or other safety devices.

### How do I clear a Rheem error code?

Rheem's manual gives a menu path for clearing alarms once the cause is dealt with:

1. 1Turn off all the hot water faucets.
2. 2Press the SERVICE button, then ENTER.
3. 3Use the up and down buttons until the display shows "Clear Alarms?" and press ENTER.
4. 4Choose "Yes" and press ENTER.
5. 5Press BACK until the initial screen returns.

If the code is still shown after that, Rheem says to turn off the hot water faucet, turn off the water heater, write down the code and call for service. Repeated clearing does not fix a problem. It only resets the display.

These are the two scale-related items on the chart, and Phoenix's hard water makes them relevant. A01L says the heater has a buildup of lime deposits. T111 is a reminder to flush the heat exchanger or replace the water treatment filter.

Rheem's manual says flushing the heat exchanger is required for maintaining optimal efficiency. It says the frequency depends on water conditions and average usage, and should be done annually or as a professional recommends. Failing to flush consistently, the manual says, could mean higher operating costs or premature unit failure. It also warns that certain water conditions can damage the heater and cause failures not covered by the limited warranty.

Rheem sells a flush kit for the job, and a service isolator valve kit with two full port valves for the inlet and outlet lines, which the manual says makes flushing and draining easier. Our page on how often to descale a tankless water heater in Phoenix covers the schedule, and our page on how hard water damages plumbing explains why the scale forms.

### What should I have ready before I call?

Rheem's manual lists what its service department asks for, and the same details help any technician. Have the model and serial number from the rating plate, the address of the heater, the name of the installing contractor, the original installation date, the dates of any past service or maintenance, and the details of the problem, including the exact code on the display. Rheem's manual says to keep the model and serial number handy because parts orders also need them, along with the gas type on the rating plate, natural or LP.

Call for any code other than the four owner steps above, for a code that comes back after you clear it, and for any code that is not on the chart. Also call if a gas smell is present at any point. HQ Plumbing and Air is licensed and insured and takes emergency calls 24/7. The estimate is free and the price is quoted upfront.

If your heater is a different brand, see our pages on Rinnai error code 11, Navien error code E003 and the full Rinnai code list. And if your Rheem is a tank model with a blinking light, see our page on Rheem water heater blinking light codes. When a tankless heater is old and the codes keep stacking up, our page on whether to repair or replace a water heater can help.

If your tankless heater is an A. O. Smith, its codes are three digits, and our page on A. O. Smith tankless error codes explains them.