Rheem Gladiator Water Heater Service Needed Light On [Solved]

Rheem gladiator water heater service needed light on tells you that there is something wrong within the heater system. Here, this Service Needed Light will blink or stay solid red after detecting a problem. 

service light on

The solid red light in an Alert indicates a disconnected leak sensor. You will find the heater remains operational during Alert. Besides, the major blinking error codes in LED include 1, 2, 3, 4, & 5. Each of the flashing red error codes is an alarm code, and the heater will shut down where it needs a special service to resolve.

Throughout this guide, we have explored every in and out of Service needed light and what to do when you encounter any Rheem gladiator error codes.

Rheem Gladiator Water Heater Service Needed Light On [Solved]

Before moving to the detailed troubleshooting part, let’s know what the service needed light feature and what its function on the Rheem Gladiator water heater. 

Note: You can also read how to fix Rheem tankless water heater won’t turn on.

What Does Service Needed Light Mean On Rheem Gladiator Water Heater

In the Rheem Gladiator water heater, there has a built-in Service Needed LED which refers to the blinking indicator of the heater. The LED starts flickering when it detects any significant problem in the heater system. 

The blinking is often a sign there is something wrong with your heater that needs your attention to get back the heater. Now the service needed LED will either stay red or blink red, telling you errors that have occurred in the heater.

Rheem Gladiator Water Heater Error Codes

While operating the Rheem water heater, users encounter several malfunctions in the system. The specific problem is then displayed on the service needed light as an error indication. A Rheem gladiator water heater has basically two types of error codes. One is Alert, and the other is Alarm. When the service needed light remains solid red, it will signify the Alert.

Besides, there have five potential Alarm codes for which the Service Needed LED will blink red at a different number of times. As the indication for each blinking far differs from each other, the solution will vary depending on the specific number of flashing. Follow the below to know what you should do to rectify the error code from the water heater.

1. Rheem Gladiator Solid Red Light [Disconnected Leak Sensor]

If the service needed light on the Rheem gladiator water heater comes on and stays solid red, it is the error indication of a disconnected leak sensor. 

It also tells you detection of a leak or  24-hour leak detection override gets activated. Rheem gladiator leak sensor reset will fix this. Also, Rheem Gladiator will remain solid red due to the following reasons:  

  • Wifi or communication control error 
  • Configuration data restore failure
  • Configuration write limit exceeded

Whatever the error, follow the below instructions to resolve the error from your Rheem gladiator.


  • Turn off the electric supply at the circuit breaker to your water heater first. 
  • Then start troubleshooting by checking the leak sensor. For this, you need to open the lower element cavity.
  • Remove the screws in the lower element cavity and inspect the leak sensor.
  • Now, look for a leak sensor if it gets detached, or it is coming loose.
  • Reconnect the leak sensor in its place snugly.
  • To fix the wifi issue, you have to reset the wifi module.
  • Press the wifi Setup button for 5 seconds, and you will hear 3 times beeping from the keypad.
  • When the wifi indicator light turns blue, set up wifi with your mobile and the heater. 
  • If still, the LED is solid red, be sure the water heater senses a leak.
  • Find the source of the water leak and fix it.
  • After that, press the Clear Alarm button for 1 second and then release it.
  • This will silence the alarm beep, and the heater will go back to its operation. 

2. Rheem Gladiator Service Needed LED Blinking Red 1 Times [Lower Thermistor Failure]

If the service needed light on the Rheem gladiator water heater blinks 1 time followed by a pause, it is the error indication of lower thermistor failure. It is sure that the lower thermistor gets disconnected from its place. Due to a faulty thermistor, the heater starts displaying inaccurate temperature readings, and the service needed light blinks 1 time.

The thermistor fails because of mechanical separation between the resistor element and the lead material. Also, due to excessive heat, the thermistor burnt out. 


  • Turn off the electric supply for the water heater in the circuit breaker.
  • Locate and inspect the lower thermistor.
  • If it is disconnected, you have to connect it properly in its place.
  • Also, replace the bad thermistor if needed.
  • As there require skills to complete the above task, it will be better to contact a professional plumber to solve the lower thermistor issue.

3. Rheem Gladiator Service Needed LED Blinking Red 2 times [Leak Detected or Shutoff Valve Error]

Rheem gladiator service needed light flickers 2 times if the water heater detection of a leak in the system. The other major reasons that are causing 2 times flickering in the service needed light include:

  • Water in contact with rope sensor
  • Shutoff valve input error
  • The shutoff valve failed to close
  • The shutoff valve failed to re-open

Anyway, here are instructions to erase Rheem leak detection and shut-off valve override error. 


  • As the rope sensor is in contact with the water, inspect the water pan first to look for water.
  • If there is no water on the pan, disconnect the sensor.
  • Let the sensor dry completely, and then reinstall it.
  • Now determine whether there is a leak in the water heart, use the 24-hour override feature.
  • If you find any excess water around the water heater, use a dryer or a shop-vac to dry out the water.
  • Now in the case of a shut-off valve error, contact a certified plumber to solve this problem. 

4. Rheem Gladiator Service Needed LED Blinking Red 3 times [Dry Fire]

Due to insufficient water in the heater tank, the service needed LED blinks 3 times. That means there is no water in the tank. Only refilling the water tank can erase this error blinking from the water heater.


  • Turn on the water supply valve to refill the tank.
  • Make sure that the drain valve and the pressure relief valve are closed while filling the tank.
  • When the tank becomes full, close the water supply valve.
  • The service needed flickering 3 times should be resolved.

5. Rheem Gladiator Service Needed LED Blinking Red 4 times [Element Wiring or Emergency Cut Out]

When the Rheem gladiator water heater service needed a light flashing red 4 times, there have a few facts that needed to be cornered. For instance:

  • Disconnection of wire either upper or lower heating element
  • Tripped ECO
  • Failure of the upper or lower heating element
  • The wiring to the ECO is disconnected.


  • If the error persists for a tripped ECO, you have to reset it.
  • Sometimes, the wires to the heater element are disconnected, which leads to the error. Reconnect the wires. 
  • But in the case of a faulty heater element, only replacing the bad element can resolve the problem.
  • Read through the below section to get an idea about how you will replace the faulty heating element.

How To Replace Heating Element In Rheem Gladiator Water Heater

  • First, turn off the circuit breaker of the water heater.
  • Remove all the attached screws from the top and bottom cavity covers.
  • Also, remove the insulation to access the element of the cavity compartment and then remove the plastic cover.
  • The heating element will be exposed. Unscrew the screws securing the wires to the heating element and remove the wires.
  • Take a 1.5” element wrench and disconnect the heating element.
disconnect the heating element
  • Install the new heating element back in place. Ensure a tightened placement of the element.
  • Then screw the wires tightly.
  • Reinstall the plastic cover and the cavity insulation.
  • Secure the cavity cover by screwing the screws.
  • Now turn on the breaker. 

6. Rheem Gladiator Service Needed LED Blinking Red 5 times [Rheem Gladiator Power Board Error]

5 blinks on the service needed light of the Rheem gladiator water heater occurs due to the following reasons: 

  • Upper or lower element relay stuck on
  • Conversions stuck error
  • Upper or lower temperature conversion error
  • Conversion drift error.
  • Temperature protection error
  • Failure or disconnection of the upper thermistor.


To deal with each of the issues that persist as an indication of 5 blinks on the service needed light, you will require professional skill. So, it will be better to contact a certified plumber to resolve the issue precisely.


Why is my Rheem water heater not getting warm?

If the water in the heater is not getting hot, be sure the problem persists from the electrical source. Either the fuse is blown, or the circuit breaker gets tripped. Sometimes, faulty heater elements cause this.

How do I flush sediment out of a water heater?

To flush the sediment from the water heater, you will need a hose and connect it to the drainage valve. Now drain and flush the water from the heater into a bucket. Do it until the water comes clear of any sediment.

Wrapping Words:

That’s all about Rheem water heater service needed light on. Throughout this article, we have walked you through each of the aspects relating to this service-needed feature of the Rheem gladiator water heater. 

Hopefully, all have become informative enough for you, and now you will resolve the errors by yourself. But still, if you have any questions, do let us know through comments. We are always here for you.

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