Three Rheem tankless codes point at an actual flame problem, not a closed valve or empty propane tank: A011 signals no flame after 10 ignition attempts, A012 means flame lit then dropped 15 times running, and A072 means flame was sensed before the igniter fired. Each traces to a different part.
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The general Rheem repair guide already carries Rheem's full tankless error code chart, sourced from the Eagle line's Use and Care Manual, so it is not repeated here. What that one-line chart cannot show is the electronic logic behind the three codes above, documented in a separate Tankless Water Heaters Technical Training and Service Manual, a document its own cover states is written for professional technicians, not for a homeowner to open the cover and test.
One more thing the chart misses. Rheem's troubleshooting guide also lists a case with no error code at all: water flows, the display shows the set temperature, and nothing heats. The manual traces that to low water flow below a 0.4 GPM minimum activation rate, a unit left in standby, or debris in the inlet filter, checked before any code-based diagnosis starts.
If your display reads 11 rather than A011, start with the owner steps in our Rheem tankless code 11 guide. A low-flow condition that shows a code is covered in the Rheem P1 low-flow guide.
Error A011 means the water heater tried to ignite and never detected a flame. Rheem's service manual says the unit attempts ignition 10 times, with a post-purge every third try, before A011 appears, and the diagnostic path checks gas pressure, filters, venting, the igniter rod, the flame rod and the gas valve.
The gas pressure check covers static pressure, on standby, and dynamic pressure, during full combustion, since another gas appliance running at the same time can pull pressure down even when the standby reading looks fine. Rheem's spec calls for 4.0 to 10.5 inches water column on natural gas and 8.0 to 13.0 inches on propane.
If the igniter's spark is not visible through the sight glass, a technician checks AC voltage across the igniter connector, expecting 108 to 132 volts; outside that range points to the igniter coil or control board, not a simple clean. If the spark is visible but no flame catches, the check moves to the flame rod and gas-air ratio valve, including a DC voltage check of 90 to 120 volts and a solenoid resistance check of roughly 313 to 347 ohms.
A loose connector reseated, a blocked filter cleaned, or a disconnected vent reattached is what clears A011 without a part order. A reading outside Rheem's documented range on the igniter, the flame rod, the gas-air ratio valve or the solenoid is what turns A011 into a parts repair instead of a reset.
Error A012 is the opposite timing problem: the burner lit successfully, then the flame dropped out during operation. Rheem's manual says the unit restarts and counts each flame loss, and only displays A012 once that has happened 15 times in a row, compared with A011's 10 failed ignition attempts before any flame ever caught.
The checklist that follows A012 overlaps heavily with A011, since a flame that will not stay lit and a flame that never starts usually trace back to the same causes: gas pressure, a blocked gas or air filter, a blocked vent connection, the flame rod, or the gas-air ratio valve. The one real difference is that A012 skips the igniter-spark check, since ignition already worked.
This is also where a widely repeated online claim gets muddled. Content describing "code 12" as flame failure is typically describing the technician-level logic above, not what Rheem's own consumer chart tells an owner to check first. On both the Eagle line and the condensing line's Use and Care Manual, the description a homeowner sees for code 12 or A012 is a gas interruption or low propane, the single most common trigger. The 15-count flame-loss counter behind it only appears in the manual written for Rheem's own technicians.
Error A072 is a false-positive fault: the flame rod reports flame present before the igniter has fired. Rheem's service manual lists two possible causes, a flame rod malfunction or a faulty gas-air ratio valve, checked through the unit's Flame Rod Status reading and a visual check through the sight glass.
If the Flame Rod Status still shows flame present with the gas and igniter both off, cleaning or replacing the flame rod is the fix Rheem's flowchart points to next. If the flame rod checks out but flame becomes visible before the igniter sparks, the flowchart calls for replacing the gas-air ratio valve instead, since gas is reaching the burner earlier than it should.
Either repair requires the Rheem-approved gasket to be replaced at the same time. The manual warns that a damaged or missing gasket on the flame rod or igniter rod can itself cause unsafe operation or permanently disable the unit's overheat limiter.
Rheem's Eagle tankless line displays bare two-character codes such as 11, 12 or 88. Its condensing tankless line, sold under both the IKONIC and Performance Platinum IKONIC names according to Rheem's own product page, displays a prefixed code instead, such as A011, A012 or T111.
The two systems are not interchangeable. The condensing line's chart documents faults the Eagle chart does not carry at all, including A029 for a blocked condensate line, since only a condensing unit produces enough condensate to clog one, plus separate thermistor codes for the heat exchanger and the exhaust where the Eagle chart lists only an inlet and an outlet thermistor fault.
Rheem's Performance Platinum condensing spec sheet lists a 0.93 Uniform Energy Factor and the same 15-year heat exchanger, 5-year parts, 1-year labor warranty already documented for the RTGH series on the general Rheem repair guide, confirming Performance Platinum is a second brand name over the same condensing hardware, not a separate warranty tier.
Code 13, an oxygen depletion sensor shutdown, appears only on the older noncondensing chart and is covered in the Rheem code 13 guide.
Yes, within the parts window. Rheem's Limited Warranty for its residential tankless gas water heaters covers component parts, which by name includes the igniter, flame rod, control board and gas valve documented above, for 5 years, while labor on that repair is covered for 1 year on a standard install.
That coverage excludes damage traced to scale or improper installation, and a repair past the 1-year labor window means the part may be free while the technician's time is not. The full warranty table by product line, and what specifically voids it, is on the general Rheem repair guide rather than repeated here.
Rheem's own service manual limits this diagnostic to a qualified technician, not a homeowner. Its cover page states the manual is written for professional technicians, and its safety section warns that the igniter cable alone carries more than 10,000 volts of electrical energy.
The homeowner-side step stays the same simple reset already covered on the general Rheem repair guide: turn off the hot water faucets, power the unit off for about 5 minutes, then restart. If A011, A012 or A072 returns after that, Rheem's own instruction is to note the code and call for service rather than opening the cover; Hot Water Brief does not perform the diagnostic itself.
Every figure above traces to a Rheem document, listed below with a link.
A011 means the water heater tried to ignite and never detected a flame. Rheem's service manual says the unit attempts ignition 10 times before displaying A011, then checks gas pressure, filters, venting, the igniter rod, the flame rod and the gas-air ratio valve.
A011 means the flame never caught after 10 ignition attempts. A012 means the flame lit but then dropped out 15 times in a row during operation. Rheem's diagnostic path for both checks the same gas, filter, venting and flame-rod causes, minus the igniter-spark check on A012.
A072 means the flame rod detected flame before the igniter fired, a false-positive reading rather than a missing flame. Rheem's service manual traces it to a flame rod malfunction or a faulty gas-air ratio valve, checked through the Flame Rod Status display and the sight glass.
Yes. Rheem's own product listing names it Performance Platinum IKONIC, and the condensing platform behind it carries the same specifications published elsewhere for the IKONIC and RTGH series, including a 0.93 Uniform Energy Factor and a 15-year heat exchanger, 5-year parts, 1-year labor warranty.
The part is generally covered under Rheem's 5-year component parts warranty on a standard residential tankless install, but labor on that repair is covered for only 1 year. Past that window the part may still be free while the labor to install it is not.
Rheem's own service manual limits this diagnostic to a qualified technician, since it requires opening the cover and testing live voltage at the control board. A homeowner's role stops at the two-step reset: turn off the hot water faucets, power the unit off, then restart.
Independent Research
Published ranges for tank and tankless replacement, the failures that justify a repair, and the ones that do not. Sourced, dated, and free to read.
