A Reddit thread in r/askaplumber about the RTEX-24’s E5 error code pulled in more than 40 replies, including one professional plumber who said flatly, “my company steers people away from electric models for this very reason.” That’s a strong statement, and it’s worth understanding exactly what’s behind it before you panic over a code on your own display.
The E5 error code on Rheem RTEX-24 units is most commonly associated with water flow problems, either insufficient flow to trigger heating or flow exceeding what the unit can handle, though some sources also point to temperature sensor malfunctions as a possible cause. Multiple independent troubleshooting sources agree the fix usually involves checking water flow rate, cleaning the flow sensor, or adjusting a water pressure regulator, rather than requiring a full unit replacement.
What E5 Actually Means
Different verified troubleshooting sources describe E5 slightly differently, which is worth being upfront about rather than picking one explanation and presenting it as the only answer. YouTube troubleshooting channel RM Info TV describes E5 as indicating “a problem with water flow overheating or a faulty sensor.” A separate video from the same channel specifically addresses an E5 variant tied to “too much water flow.” JustAnswer’s plumbing experts describe the E5 code as indicating “a temperature sensor malfunction” specifically.
The common thread across all these sources is that E5 relates to the unit’s ability to correctly read and respond to water flow and temperature conditions, not a catastrophic hardware failure in most cases.
Common Fixes, Based on Multiple Verified Sources
Across the troubleshooting guidance available, a few consistent recommended steps show up repeatedly:
Check your water flow rate and consider adjusting a water pressure regulator if flow is too high or too low for the unit’s current configuration.
Clean the water flow sensor, since mineral buildup or debris can interfere with accurate flow readings, triggering the error even when the unit itself isn’t damaged.
Attempt a reset of the unit following the manufacturer’s documented reset procedure, since a temporary sensor glitch can sometimes resolve with a simple power cycle.
Verify all wiring connections are secure, since JustAnswer’s plumbing experts specifically recommend this as a first troubleshooting step for temperature sensor related codes.
When E5 Signals a Bigger Problem
Real reviewer accounts show this error can also appear when a household’s demand genuinely exceeds what their specific installation can support, whether due to cold groundwater requiring more temperature rise than available, insufficient electrical capacity, or a household running more simultaneous fixtures than the unit’s current configuration allows. In these cases, the error isn’t really about a faulty component, it’s the unit correctly signaling it can’t safely meet the current demand.
Should You Call a Professional?
If basic troubleshooting (checking flow, cleaning the sensor, confirming wiring, attempting a reset) doesn’t resolve the E5 code, it’s reasonable to call a licensed plumber or the manufacturer’s support line rather than continuing to troubleshoot electrical components yourself, particularly given the voltage involved in these units. The Reddit plumber’s comment about steering customers away from electric models specifically reflects real frustration with this exact error appearing repeatedly in certain installations, underscoring that persistent E5 errors are worth a professional diagnosis rather than repeated DIY attempts.
For the full reset procedure and additional troubleshooting steps beyond error codes specifically, see our reset guide.
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The Bottom Line
The E5 error code on the Rheem RTEX-24 generally relates to water flow or temperature sensor issues, and common fixes include cleaning the flow sensor, adjusting water pressure, and confirming secure wiring. If basic troubleshooting doesn’t resolve it, especially if the error recurs consistently, a professional diagnosis is the safer next step given the electrical complexity involved.
Frequently Asked Questions
What does the E5 error mean on a Rheem RTEX-24? E5 is most commonly associated with water flow issues, either insufficient or excessive flow, though some sources also point to temperature sensor malfunctions as a possible cause.
How do I fix the E5 error on my Rheem RTEX-24? Common fixes include checking and adjusting water flow rate, cleaning the flow sensor, confirming secure wiring connections, and attempting a manufacturer-recommended reset.
Why does my Rheem RTEX-24 show E5 only in one shower? This pattern, reported in real user discussions, often points to a flow or pressure issue specific to that fixture’s plumbing rather than a unit-wide failure.
Can I fix the E5 error myself? Basic troubleshooting steps like cleaning the flow sensor or checking water pressure are often manageable for handy homeowners, but persistent issues may require a professional diagnosis given the electrical complexity of the unit.
Does the E5 error mean my Rheem RTEX-24 is broken? Not necessarily. It often indicates the unit is detecting a flow or sensor condition it can’t safely process, which can be a configuration or maintenance issue rather than a hardware failure.
Is E5 a common error on the Rheem RTEX-24? Based on the volume of troubleshooting content and forum discussions dedicated specifically to this code, it appears to be one of the more frequently reported error codes for this unit.
Should I call a plumber or electrician for an E5 error? If basic troubleshooting doesn’t resolve it, a licensed plumber experienced with tankless systems, or the manufacturer’s support line, is a reasonable next step before assuming the unit needs replacement.
Can hard water cause the E5 error? Yes, mineral buildup can interfere with the flow sensor’s accuracy, which several troubleshooting sources identify as a contributing factor to this error.
Does adjusting water pressure really fix the E5 error? For cases where the error relates to flow rate being too high or too low, yes, adjusting a water pressure regulator is a commonly recommended and effective fix according to multiple troubleshooting sources.
Is the E5 error covered under warranty? Check your specific warranty documentation, since coverage can depend on whether the issue is determined to be a component defect versus an installation or water condition issue.
References
- JustAnswer plumbing expert guidance on Rheem tankless water heater E5 error codes, accessed July 2026: https://www.justanswer.com
- RM Info TV troubleshooting guidance for Rheem tankless water heater E5 error code, accessed July 2026
- Reddit r/askaplumber community discussion of Rheem RTEX-24 E5 error experiences, accessed July 2026