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

Resetting a Rinnai is not one procedure but a family of them — a plain controller cycle for most faults, a five-press pattern that means opposite things on LC and SS, a latching A/B-button sequence at the PC board for codes 17 and 52, and hard power resets for 57 and 58. This guide walks through what Rinnai actually documents: how to do the owner reset correctly, how to read and preserve the fault history before you clear anything, and the point at which a returning code stops being a reset question and becomes a diagnosis. Every procedure below is the manufacturer's own, quoted from the manuals and tech sheets, with the owner steps and the technician steps kept visibly separate.

What a reset can and cannot do on a Rinnai

A reset clears a display and permits a new attempt; it repairs nothing. Holding that distinction is the whole discipline of this page. Rinnai's controllers are designed so that a transient event — a gas interruption, a power flicker during bath fill, a gust-driven flame loss — does not become a service call: the fault is shown, the owner cycles the controller, the heater tries again under normal conditions and, if the event has passed, runs. The same design makes a reset a diagnostic instrument: performed once, under recorded conditions, it separates the transient from the persistent more reliably than any guess. What a reset cannot do is alter a physical state. Scale remains in the exchanger after an LC reset — Rinnai builds a counter into the system precisely to prevent that misunderstanding. A blocked venturi remains blocked after power-cycling a 17, which is why that code is latched behind a board-level procedure instead. A tripped thermal fuse does not heal. The manuals' structure teaches the rule by repetition: for code after code, the documented sequence is correct the cause, then reset by the method that code specifies. Owners who invert the sequence — reset first, repeatedly, and investigate never — are not doing anything the manufacturer recognises as troubleshooting, and in the case of combustion faults they are spending the heater's safety margins on postponement. One reset, observed properly, is maintenance. The second identical reset is a phone call. Keep that sentence in mind at the controller and every procedure in this guide falls into its proper place: resets conclude diagnoses, they do not replace them.

The standard controller reset, step by step

For the general run of two-digit faults, Rinnai's owner reset is a controller cycle, and its bath-fill form is the one the manuals spell out word for word. Step one: turn off all hot water taps and fixtures — the heater should be at rest, with no draw confusing the test. Step two: press the ON/OFF button on the temperature controller to turn it off, then press it again to turn it on; for code 03 (power interruption during bath fill) the documented instruction is literally 'press ON/OFF twice'. Step three: open one hot tap — a single, moderate draw, ideally the tap whose behaviour you can observe — and watch one complete attempt: fan, ignition, sustained hot water, or the code's return. Step four: record the result before touching anything else: cleared and held through a full draw, cleared then returned during the draw, or never cleared at all. Those three outcomes are three different diagnoses, and they are only available if the test was controlled. Practical notes from the manuals' margins: the controller does not switch the heater's electrical power — a true power reset means the plug or the breaker, which is the documented route for older Non-SENSEI LC clearing and for the hard resets of codes 57/58 — and a heater on a remote controller is reset at the controller that is displaying the code. If the display is blank rather than coded, that is not a reset problem at all: it belongs to Rinnai's 'No Code' procedures (power, flow and connections), and no button pattern substitutes for them.

Read the fault history BEFORE you reset

Every reset destroys evidence unless you collect it first, and on a Rinnai the evidence is one button combination away. With the heater turned off at the controller, press and hold ON/OFF for two seconds, then press the UP button at the same time: the controller displays the last nine maintenance codes, flashing them one after the other. Transcribe them in order, exactly — including the entries that look like non-events. FF in the list is the timestamp of the last professional service. An entry of 00 is not a code zero: it is how the history stores an LC scale event. A run of identical codes dates a persistent fault; a progression (10, then 12, then 11) narrates a deterioration that a single current code conceals. To exit, repeat the ON/OFF-plus-UP combination and turn the heater back on. The same controller family offers a second, related view — performance data, reached by holding DOWN and then ON/OFF together, then scrolling with UP/DOWN: item 01 is water flow rate in tenths of a gallon per minute, item 02 the outgoing temperature, and so on through fan and temperature values. Performance data answers 'what is the heater doing right now'; fault history answers 'what has it been through'. For any code that will become a service call, the thirty seconds spent transcribing the history is the highest-value action available to an owner — technicians are trained to read that sequence first, and arriving with it written down measurably shortens the visit.

The five-press pattern: LC and SS, same gesture, opposite meanings

Pressing ON/OFF five times within five seconds is Rinnai's best-known button pattern, and it is dangerously easy to misunderstand, because the same gesture serves two displays with opposite intent. On SS — the Service Soon reminder, also shown as 55 — five presses on a SENSEI model simply acknowledge and clear the time-based reminder after service has been done (on RX/CX models the reset is different: hold the 'A' button on the PC board until SS disappears). It is a clerical act, closing a scheduled interval. On LC, the identical gesture is a temporary override with a meter running: it restarts a heater that has locked out for scale, for up to 70 hours of operation, while the controller continues cycling the LC reminder — and each repeated use advances the displayed count, LC1, LC2 and upward. Rinnai's own worked example: LC2 means three 70-hour periods used without a flush. The gesture that politely files SS therefore, on LC, signs a promissory note against the heat exchanger. The rule that keeps them straight: five presses are the FINISH of an SS service, and only ever a BRIDGE to an LC flush — arranged, dated and actually carried out. If you use the pattern on LC without booking the flush in the same conversation, you have not reset the heater; you have started its counter.

Latched codes and hard resets: 17, 52, 57, 58 and the LC hard reset

A tier of Rinnai codes is deliberately not owner-resettable, and recognising the tier saves futile evenings of power-cycling. Codes 17 (venturi blockage) and 52 on SENSEI models share a dedicated clearing procedure performed at the PC board with the front panel off: with the controller off, button B is pressed in steps to walk the display through a sequence — t, F, S on SENSEI — to 'E', a step that only exists while 17 or 52 is active; then buttons A and B are held together for 10 seconds until the display shows 'ECL', reset complete. RX/CX models walk a longer sequence (dES, t, AdJ, F, A, E) to the same ECL. The procedure exists so the code cannot be cleared without the hardware having been opened and the venturi or valve actually serviced. Codes 57 and 58 use a different latch: correct the bi-metal switch cause first, then a hard reset — power off at the supply, then back on. The LC hard reset belongs to the same tier: after a completed flush, if the code has not self-cleared (RX/CX clears automatically after a proper flush), switches A and B are pressed together for five seconds to return the LC count to zero — a step Rinnai notes is not published in the owner's manual. Common thread: everything in this tier is done by the service technician as the final act of a physical repair. An owner who finds instructions for these sequences on a forum and performs them without the repair has defeated an interlock the manufacturer built on purpose.

When the code returns: reading the pattern

A returning code is not a failed reset; it is a successful test with a negative result, and its timing refines the diagnosis every time. Returns immediately, on every attempt, before any hot water: the cause is present and total — a closed gas supply on an 11, a short on an immediate 12, a vent that cannot move air on a 10. Returns only under load — big draws, multiple fixtures, the coldest mornings: the cause is marginal capacity, classically gas pressure that sags at high fire, or a vent/fan path that almost suffices. Returns after days or weeks of clean running: the cause is progressive or environmental — scale rebuilding toward its next LC, a condensate line re-clogging, debris accumulating at a venturi or a termination. Returns accompanied by a second code that was not there before: read the pair as one story in the fault history, not two faults. And one pattern overrides all others: any code that returns with a new physical symptom — a gas smell, burning or discolouration, water where water should not be, breaker trips — ends the reset experiment on the spot, whatever the code. Write the pattern down in the form 'code, condition, interval' (for example: 12, only on two-fixture draws, since October). That single line, plus the transcribed history, is a professional-grade service report, and it is produced entirely by resetting once and watching properly.

Reset safety rules that outrank every procedure above

Four rules from Rinnai's own safety text govern every reset on this page. First, the gas rule, verbatim in substance: if you smell gas, do not try to light any appliance, do not touch electrical switches, do not use a phone in the building — leave, and call your gas supplier from a neighbour's phone or outside; if you cannot reach them, call the fire department. No reset step is ever performed through a gas smell. Second, the panel rule: the heater must not be operated with its front panel removed — the panel comes off for service and goes back on before operation — so any 'reset' that requires the cabinet open is definitionally not an owner reset. Third, the adjustment rule: do not adjust the internal gas valve for any code; Rinnai states the design requires no adjustment and that doing so voids the warranty — several codes (15, 18, 52, 71) tempt exactly this error. Fourth, the water rule: on code 79, and on any sign of water inside the cabinet, the first control to touch is the water supply shutoff, not the controller. Within those fences, the owner's reset craft is genuinely useful — one controlled controller cycle, a transcribed history, a timed observation. Outside them, the buttons are not a toolkit; they are the heater asking, as politely as it can, for a professional.

Keeping a reset log the technician will thank you for

A reset log sounds like bureaucracy until the second time a code appears, when it becomes the diagnosis. Rinnai's system is built to be read longitudinally — the controller itself keeps the last nine codes — and an owner's log extends that memory beyond nine events and adds the context the controller cannot store. Keep it to four fields per entry and it takes under a minute: the date and time; the code exactly as displayed, including any LC digit; the conditions (which fixtures were running, the weather if the vent or condensate could be involved, any recent work on gas, water or the heater itself); and what you did, with the result stated in the three-outcome form — cleared and held, returned during the draw, never cleared. Three entries are usually enough to see a pattern a single event hides: the 12 that only follows a two-fixture draw, the 10 that only follows freezing nights, the LC whose interval is shortening quarter by quarter. Bring the log to every service visit and quote from it when booking. It changes the conversation in a specific way: the technician stops pricing possibilities and starts testing the one the evidence already points to. It also protects you in both directions — it documents a fault that predates a repair if the same code returns after one, and it documents your own resets honestly if a warranty question ever turns on how the heater was treated. No tool in this guide costs less or earns more. Photographing the controller at the moment of transcription is the belt-and-braces version of the same habit: a photo preserves the exact display, including flickering segments a hurried eye can transpose, and timestamps itself for free.

Key takeaways

• Transcribe the last-9 fault history (hold ON/OFF 2 seconds, then press UP) before every reset — resetting first erases your best evidence
• ON/OFF five times in five seconds is a post-service acknowledgement on SS, but only a 70-hour bridge loan on LC — never use it on LC without booking the flush
• Codes 17 and 52 cannot be cleared at the controller at all: their ECL reset happens at the PC board as the last step of a physical repair
• Judge a reset by one full, controlled hot-water draw: cleared-and-held, returned-during-draw, and never-cleared are three different diagnoses

Resetting the Rinnai water heater

The standard owner reset is a controller cycle: close the hot taps, press ON/OFF to turn the controller off, then on again, and run one test draw (code 03's documented form is ON/OFF twice). Special codes have special resets that are not interchangeable: LC and SS use five ON/OFF presses within five seconds (LC's version is a 70-hour temporary reprieve, not a cure); codes 17 and 52 clear only through the PC-board A/B-button sequence ending in 'ECL'; codes 57 and 58 need a hard reset — power off, then on — after the cause is corrected; and the LC hard reset after flushing is the A/B switches held together for five seconds. One reset, then observe: a code that returns is a live fault reporting itself, not a reset that 'didn't take'. Document the outcome of every reset you perform — cleared and held, returned during the draw, or never cleared — because that record is what turns a home reset into diagnostic evidence.

Frequently asked questions

Related guides

Facts on this page were checked against manufacturer documentation: www.rinnai.us · media.rinnai.us · www.rinnai.ca · media.rinnai.us · www.manualshelf.com · www.rinnai.us