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Brand:thermador
Model Number:PRG366GH/21
Main Symptom:EX-LOW FEATURE IGNITER FIRING RANDOMLY
What happens & when:FIRING
Error Code (if any):
Parts or tests already tried:
Photos / video link:
More than likely, this is a potentiometer failure. However, it can be tested when the igniter is firing to verify if it is the cause, or if the simmer controller is the issue. If you remove the knobs and the console plate, the potentiometer would be tested from the blue wire to the yellow wire (front left burner) or from the blue wire to the violet wire (rear left burner) for DC voltage. Does it show 1.5 Volts DC? If it does, the potentiometer has failed. If not, the simmer controller is the issue. Here are links to each part for reference.
Potentiometer- 00629722 Potentiometer (Control Knob Input), 1 | Genuine Bosch OEM In Stock
Simmer control- 00619016 Fixing Kit | Genuine Bosch OEM In Stock
Hi William,
Thermador replaced both X-Lo potentiometers twice under warranty. I don’t recall if they performed any trouble shooting or just went for the replacement. The igniter firing problem is intermittent. Sometimes no problem for a month or more. Otherwise all the burners and igniters work as designed.
Thermador says it can be caused by moisture or a grounding problem. All that is fine. I have had the igniters out several times. No moisture and no corrosion and good grounding. Everything looks like new.
Would the Simmer Control board affect the other four igniters? No problem with them.
We will never use the X-Lo feature. Is there a way to by-pass it by removing a wire to that unit?
Thanks for the help!
Chris
Sorry, forgot to ask this. I have two of the replaced potentiometers. Can I bench test them to see if they show signs of failure or intermittent action? There are 5 connector pins. Do you know how I can test the X-Lo side of the potentiometer? I presume with a Volt/Ohm meter we can check, but it may require voltage applied to the circuit board. See attached photos.
Thanks,Chris
The simmer controller would not affect the other burners. Unfortunately, the wiring diagram does not show which pin connects where in the potentiometer. It only shows the pathway by how the wires are routed. Moisture at the potentiometer can cause enough voltage to pass through to signal to the simmer control that the igniter needs to spark. Is the range being cleaned immediately before the igniter starts sparking on its own? Also, how long ago were the potentiometers replaced?
After replacement of the potentiometers, the problem was still intermittent. Again, intermittent might be one month to three months between this false igniter firing. We only know when we are home. If not home they can mis-fire for hours and we would never know it.
We were due for a third set of potentiometers under warranty, but we said the hell with it. They scratched our SS unit on the prior visit and we didn’t want them here again.
Usually it is one X-Lo igniter that’s the problem, but the other X-Lo will do it on occasion and they both had the potentiometer replaced. Are we getting defective replacement parts?? Can you please check the history on this part from your sales team? They are OEM replacements.
Per owners manual Trouble Shooting, it states intermittent igniter sparking could be a cause of ceramic igniter wet or dirty, or burner ports are plugged. Also, CONSTANT igniter sparking could be range not properly grounded or electrical power supply is incorrectly polarized.
I believe they refer to moisture around the igniter and not the control knob. They are probably thinking boiling water overflowing and running into the igniter well. Not the case with us.
Thank you.
Chris
It’s very possible you’re dealing with a simmer control failure. The simmer control is what sends voltage to the igniters after it receives a signal from the burner potentiometers. Since it’s unlikely that multiple potentiometers would fail at the same time, the simmer control becomes the most probable culprit.
Unfortunately, the only reliable way to confirm this is to test the circuit while the failure is actually happening. That’s when you can see whether the simmer control is receiving the signal voltage when it should not, or if it is sparking on its own.
Hi William,
Testing at time of failure will be tough. I will just replace the Simmer Control board. Do you have instructions for this? Did you get a chance to ask your sales team if new potentiometers are commonly failing? Can you see how many of these Simmer Control boards have been sold for my unit?
Thank you for the help!
Chris
Accessing the simmer control for replacement is going to be the same console removal process used for testing from what I can see. There are not any factors I can see that would correlate to faulty potentiometers recently. There have been several simmer controls through the year.
