Rheem Water Heater Reset: How to Reset & Clear Error Codes

Resetting a Rheem water heater is not one procedure but four — one per platform — and using the wrong platform's reset is the most common reason 'the reset didn't work'. This guide gives the documented procedure for each system: the tankless five-minute reset and its IKONIC display variant, the DIP-switch hard-lockout procedure with its CL and UL confirmations, the tank gas control (which has no reset button at all, on purpose), and the EcoNet hybrid and smart electric alarm-clearing routes — finishing with the codes you should never reset-and-ignore, because the reset is not the repair.

Before any reset: read, record, and fix the obvious

Every Rheem reset procedure assumes something owners routinely skip: the code gets read and the cheap causes get checked before the clearing starts. A reset does not repair anything; it tells the control to try again. If the reason for the shutdown is still present — an empty LP tank, a blocked vent termination, a full condensate trap, a tripped high limit with a failed thermostat behind it — the control will simply shut down again, and on some platforms repeated casual resets escalate the situation into a hard lockout that needs the formal procedure. So the pre-reset routine is fixed: note every code displayed (and scroll the fault history on models that keep one — IKONIC tankless units store recent faults, and the troubleshooting manual's maintenance mode shows the last 8 at the *E positions); check the boundary causes an owner can see — gas valve fully open, LP in the tank, both vent terminations clear, condensate draining, breakers on, filter screens clean; and only then clear, once, and watch the result with the tap running. What happens in the first minutes after a correct reset is diagnostic gold: instant re-trip means a hard fault, re-trip under load means a supply or capacity problem, and a clean run means the event may genuinely be over. Reset blind and you learn nothing; reset last and you learn everything.

Tankless reset: the documented five-minute procedure (RTGH / RTG)

Rheem's Use and Care documentation for tankless models gives the clearing procedure in plain steps: close the hot water faucet, turn the remote control off, wait 5 minutes, turn it on again, and open a hot water faucet. If the code is still displayed after those steps, the same text closes the loop — close the faucet, turn the water heater off, and call a qualified service technician (the manual's wording covers codes not in its chart as well: if an unlisted code is displayed, turn the unit off and call for service). Rheem Australia's continuous-flow guide documents the fuller version of the same ritual and adds two steps worth adopting everywhere: switch off the electrical supply to the unit during the wait, and — before restarting — check that the gas isolation valve is fully open; then switch the power on, turn the controller on, and open a hot tap. The 5-minute wait is not superstition: it lets the control's capacitors drain and its lockout timers expire, and it lets a hot heat exchanger cool toward a state where a fresh ignition attempt is meaningful. Variants to avoid improvising: unplugging for five seconds (too short for the timers), flipping the breaker repeatedly (teaches nothing, stresses the control), and resetting with a hot tap open (the manual's sequence is faucet closed first, for a reason — the unit should restart into a controlled call for heat, not a chaotic one).

IKONIC displays and hard lockouts: ENTER, DIP switches, CL and UL

Newer IKONIC-generation tankless units offer a civilised front door first: on the built-in display, press ENTER, and when 'Clear Alarms?' appears, answer Yes. Use it for ordinary codes after the cause is addressed. Behind that front door, though, sits the formal procedure Rheem reserves for hard lockouts — the manual heads it 'Reset Procedure / Clearing Fault History' and names the offenders, codes 10, 13 and 99: faults where the control has stopped accepting casual retries (13 earns it by shutting down 5 times within 4 hours). The procedure is deliberately mechanical, and it is technician-shaped: turn the remote control off but leave the unit plugged in; remove the front cover; locate the DIP switches at the upper right of the control board; ensure all DIP switches are off; flip DIP1 switch 1 (fault-history clear) or switch 2 (lockout reset) on and immediately off; then within 5 seconds press and hold the MIN and MAX buttons for at least 2 seconds. The remote's answer tells you which half you performed: it flashes 'CL' then holds it solid when the fault history has been cleared, and 'UL' for the reset. You can verify the clear in maintenance mode — the fault history location (1E) should read NULL. Because this procedure involves the open cabinet and board-level switches, most owners should hand it to a technician; if you do perform it, restore the cover, turn the remote on, and run a hot tap while watching the first full heating cycle.

Tank gas controls: the reset that does not exist

Owners of tank gas heaters with the electronic combination gas control go hunting for a reset button that Rheem never fitted — and that absence is a design decision, not an oversight. This control is powered by its pilot's thermopile and supervised by its status LED; it has no memory to clear and no lockout counter to forgive. Its faults clear when their causes clear: a weak thermopile replaced restores the voltage and the 2-flash pattern stops; a pilot relit correctly returns the control through its steady-light cool-down to the 1-flash heartbeat. The chart's fault entries — 4 (high temperature shutdown), 5 (sensor failure), 7 (control/valve failure), 8 (flame sense error) — are directed by Rheem to a qualified service technician precisely because none of them is a 'try again' condition: each is a component or safety verdict. The only reset-adjacent owner actions on this platform are the legitimate restarts: relighting the pilot strictly by the label instructions after the LED has gone dark, and turning the temperature dial back to a sane setting if it was disturbed. Resist internet folklore about button combinations on this control — the famous arrow-key sequences belong to other systems (the IntelliVent's flammable-vapour lockout ritual circulates widely but is not documented in Rheem's materials for this control), and performing undocumented rituals on a gas valve is how small problems become large ones. IntelliVent power-vent models are the exception that proves the rule: their maker's guide does document a power reset — off for 10-20 seconds, then on — for most of their fifteen codes.

EcoNet, hybrid, and smart electric: clearing alarms without hiding them

On hybrid heat-pump and smart electric models, 'reset' means clearing alarms through the control — and the discipline is to read them first: on the hybrid display, press Next until 'Current Alarm' is visible and scroll with the Down arrow, noting every active alarm before anything is cleared. Many hybrid alarms clear themselves once the condition is corrected — clean the filter screen behind a T131 reminder or an airflow-related A005, unclog the condensate line behind A108, fill and purge the tank behind an A008 dry-fire — because the control continuously re-reads its sensors. The one documented override deserves its own warning: the A107 leak alarm can be silenced for 24 hours by holding the Clear Alarm button for 5 seconds, a feature designed to keep a household in hot water while a leak is being fixed. Using it without fixing, or renewing it day after day, converts a leak alarm into background noise while water damages the home — the manual's framing assumes the override and the repair happen in the same 24 hours. Smart electric (Gladiator-style) controls add a simpler gesture: pressing the CLEAR ALARM button for about a second silences the beeper, which is an acknowledgement, not a repair. And some alarms must never be 'cleared' by an owner at all: an ECO high-limit trip (hybrid A200, smart-electric A104 family) means the primary temperature controls failed once already; that heater stays off until a technician finds out why.

Electric tankless (RTEX/EcoSmart): power-cycle discipline

The electric tankless platform has the simplest reset story and the easiest to get wrong by overcomplicating it. Its E-codes are mostly live conditions rather than latched lockouts: E5 (high flow rate) clears the moment flow drops back inside the unit's capacity, and needs no reset at all; E4 (high temperature) requires the water and exchanger to cool and the flow restriction behind it to be removed. For a display that seems stuck after the condition is corrected, the correct move is a clean power cycle at the breakers: all of the unit's circuits off together, a full minute of patience, then all back on together — these heaters are fed by multiple breakers, and cycling only some of them, or flipping them in a scattered sequence, can leave the control in a half-powered state that manufactures fresh confusion. Thermistor faults (E1, E2, E3) and low voltage (S103) will survive any power cycle, because they describe hardware and supply, not events: a sensor reading out of range at power-up simply re-posts its code, which is the control correctly refusing to be talked out of a measurement. So on this platform the rule inverts the tankless pattern: reset freely for condition codes once the condition is fixed, and do not reset at all for sensor and voltage codes — those go straight to the service call, with the unit's breakers off in the meantime if the code involves temperature sensing.

When not to reset: the codes that are the diagnosis

A short list of Rheem codes should never be met with a reset as the main response, because in each case the shutdown is the only thing standing between a fault and a worse outcome. Over-temperature events — tankless 14 (overheat limiter) and 15 (excessively hot water, defined by Rheem as above 207 F for more than 15 seconds), the tank-gas 4-flash high-temperature shutdown, hybrid A200's tripped ECO, smart-electric ECO alarms — all mean a primary control already failed to limit temperature once; resetting re-arms the same failed arrangement. Flame-integrity codes — tankless 72 (flame sensed before ignition) and 80 (flame still sensed after the gas valves closed, 'gas cut-off defective' in Rheem Australia's words) and the tank-gas 8-flash false flame signal — accuse the single most safety-critical sensing in the appliance; a control that cannot be trusted about flame must not be given repeated chances. Control self-verdicts — 7 flashes, tankless 70 (microcomputer abnormality), 71 (solenoid drive circuit) — are the electronics reporting internal failure; a reset cannot un-fail a circuit. And leak codes — tankless 17, hybrid A107 — protect property rather than people, but water damage compounds hourly, and every reset without a found source is expensive. For all of these, the owner procedure is identical and short: make it safe (power off, water or gas isolated as appropriate), write down the code, and call the professional whose trade the code belongs to.

After repairs, outages and holidays: resets in real life

Three everyday situations produce more reset confusion than any fault. After a repair, the first start is a verification, not a formality: a replaced control board may need its alarms cleared from the display, a tankless unit should be run through a full call for heat while someone watches the first ignition, and a hybrid should be checked an hour later to confirm the alarm list is empty rather than refilled — several alarms only post under sustained operation. After a power outage, platforms behave according to their power source: a tank gas heater on a thermopile-powered control never noticed the outage (its pilot powers it), which surprises owners pleasantly; tankless and hybrid units reboot their electronics and generally resume, but a unit that was mid-fault when the power died will usually re-post its code after the reboot — that is memory, not a new failure. After a holiday, the common trap is the reverse: a heater left in a vacation or low mode, or isolated at its valves, gets blamed and reset when it was simply configured. Check the mode, the valves, and the temperature setting before any procedure in this guide. In all three situations the discipline is identical: establish what state the heater is actually in, clear only what a documented procedure clears, and verify with a watched heating cycle before declaring the episode closed.

A reset that holds: confirming the repair, not just the restart

The difference between a reset and a repair is what happens over the following week, so finish every reset with verification. Run a full, honest heating cycle and stay for it: a tankless unit should light promptly, hold a steady outlet temperature at a normal tap, and shut down cleanly when the tap closes — no short-cycling, no second code, no combustion smells. On a hybrid, confirm the mode you expect actually engages (heat-pump hum versus silent element heating) and re-check the alarm list an hour later, because several alarms only post under sustained run conditions. On a tank gas control, confirm the LED has settled to its 1-flash heartbeat and stays there through a burner cycle. Then log it: date, code, what you found, what you did. That small record transforms the next event — a code that returns in 6 months with the same signature is a pattern a technician can solve in one visit, while an unrecorded repeat looks like a brand-new mystery. And if the code returns inside the verification cycle itself, stop resetting entirely: you have performed the experiment Rheem's manuals prescribe, the hypothesis 'transient event' has been falsified, and the remaining explanations all live inside the cabinet.

Key takeaways

• Universal order: read and record the code, check the boundary causes (gas, vents, drains, breakers), fix what you find, reset once, then watch a full cycle.
• Tankless standard reset: faucet closed, controller off, power off, 5 full minutes, power on, controller on, open a hot tap. IKONIC: ENTER, then Yes to 'Clear Alarms?'.
• CL and UL on a tankless remote are success messages from the hard-lockout procedure (history cleared / reset done) — not new faults.
• Tank gas combination controls have no reset button by design; faults clear when their causes are repaired. Relight pilots by the label only.
• Never reset-and-ignore overheat (14, 15, 4 flashes, A200), false-flame (72, 80, 8 flashes), or leak codes (17, A107) — those go to a professional.

Resetting the Rheem water heater

Each Rheem platform resets the way its manual documents, and only that way. Tankless models: close the hot faucet, turn the controller off, switch off the electrical supply, wait 5 minutes, restore power, turn the controller on, and open a hot tap; IKONIC displays also clear alarms via ENTER and 'Clear Alarms?' — Yes; hard lockouts (10, 13, 99) have a DIP-switch procedure that ends with the remote flashing CL (fault history cleared) or UL (reset confirmed). Tank gas controls have no reset button: the status LED clears when the underlying fault clears, and Rheem's chart routes 4, 5, 7 and 8 flashes straight to a qualified technician. Hybrids and smart electric tanks: read and note the alarm first (Next / Down arrows on the hybrid display), fix the cause, then clear; a leak alarm such as A107 can be overridden for 24 hours only by holding Clear Alarm for 5 seconds — time bought to arrange the repair, not to skip it. One reset after fixing the cause is the documented pattern on every platform; repeated resets against a live fault are not a strategy.

Frequently asked questions

Related guides

Facts on this page were checked against manufacturer documentation: files.myrheem.com · files.myrheem.com · www.manualshelf.com · www.manualshelf.com · www.manualshelf.com · mans.io · manuals.plus · manuals.plus · manuals.plus