Rheem Tankless Water Heater Error Code c7 (How To Fix)

Rheem tankless water heaters are modern and automatic, and they heat water much faster than older tank water heaters. However, error codes can appear from time to time, and the error code c7 is quite common. So, what does “c7” mean, and how do you fix it? 

A c7 error code on your Rheem tankless water heater indicates a problem with the main circuit board or PCB. It could also indicate a faulty remote or damaged wiring between the heater and the remote. Easy fixes include replacing the remote or control board and servicing the water heater. 

Let’s look at the common causes for an error c7 on a Rheem water heater and examine easy fixes to these problems. 

1. The PC Circuit Board Is Damaged

Rheem Tankless Water heater circuit board
Source: https://youtu.be/dV2rdZ0cMFE?t=1130

A damaged circuit board means that your water heater can’t interpret the remote’s signals, which may cause the malfunction. When you get the error code, you’ll also notice that the water isn’t warming up as much as it should, or it may not get hot at all. 

Since a damaged circuit board is usually a major problem, you want to be 100% sure that it’s what’s causing the c7 error code. To do so, you’ll have to disconnect the remote wiring. Follow these steps to test your Rheem tankless water heater’s circuit board: 

  1. Disconnect the power source from the water heater. 
  1. Remove the cover and disconnect the remote’s wiring from the heater. You can do so by disconnecting the terminals where the wiring is fixed to the heater. 
  1. Turn the power back on and test the water heater. If the water heater switches on when you turn on the hot water tap, then there’s nothing wrong with the circuit board. 

If the water heater doesn’t work when you disconnect the remote wiring, the error is caused by a damaged circuit board. 

How To Fix 

The best way to fix a damaged Rheem tankless water heater circuit board is to replace it. You can also have a qualified technician repair it, depending on whether you have time left on the warranty. 

fixing water heater

Rheem water heaters usually have a warranty of six years, depending on your area. If you purchased your water heater recently, you can get the circuit board repaired or replaced at no extra cost. 

If you have an older water heater, I strongly recommend replacing the circuit board since repairs don’t last very long. 

2. The Remote’s Wiring Is Damaged

If your Rheem water heater doesn’t work after you disconnect it from the remote wiring terminals, the problem is either with the remote’s wiring or the remote. Wiring problems are usually rare, so it’s best to eliminate the possibility before checking the remote. 

The wire may be damaged by water or high temperature, or it may have just disconnected from the wire terminal. 

How To Fix

To determine whether the remote’s wiring is faulty, replace the existing wiring with 18 gauge wiring. Connect the terminals properly and test the water heater. 

If the water heater works properly when you place new wiring, leave the wiring in. If it still doesn’t work, the problem is with the remote. I recommend leaving the new wiring in, as there may be a problem with dual wiring and the remote. 

3. The Remote Is Faulty 

If you’ve replaced the wiring connecting the remote to the circuit board and the water heater still doesn’t work, the remote may be damaged. This may be a minor issue, such as a problem with the remote switch, or the remote may be completely broken. 

How To Fix 

While you can take the remote to a repair shop, the best solution is to replace the remote. If you’ve bought the water heater recently, you can contact Rheem support to check whether the remote comes under the warranty. 

If not, you can purchase a new remote from Rheem.

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4. The Water Heater Needs Maintenance

A lack of maintenance may also cause the water heater to display a c7 error. This is because the c7 error is often a sign of an electrical problem and may also be caused by dirt or dust interfering with the sensors around the pipes. 

water heater maintenance

Blocked water pipes may also cause the water heater to malfunction since the flowing water activates the automatic switch. In such cases, you may also get a p1 error code

How To Fix 

The best way to fix maintenance problems is to do yearly and monthly maintenance! Have a professional de-lime and clean the water heater and combustion parts yearly. Also, make sure you clean the water filter once a month to prevent dirt build-up. 

Here’s a video guide on how to clean the water filter of a Rheem tankless water heater: 


A c7 error code on your Rheem tankless water heater indicates an electrical problem with the circuit board or remote wiring. It could also mean your remote is faulty. If the circuit board or remote is damaged, you can replace it. 

Also, complete monthly and yearly maintenance tasks to ensure your water heater functions properly.