Joe Traeger developed the Traeger pellet grill in 1985 and patented it in 1986. Early Traeger Grills, as well as many of the pellet grills first introduced after the expiration of the Traeger patent, used a three-position controller, called an LMH controller indicating settings for low, medium and high heat. Each setting approximates a temperature range, and those temperatures were achieved by means of a fixed, predetermined duty cycle. Furthermore, because the duty cycles are fixed, they don't account for weather conditions or the amount of food being cooked, both of which affect temperature.

Gas Grill Error Codes

HEr 
Nope, your grill isn’t female. This one stands for “High Temperature Error.” 
You’ll see this appear on your Traeger’s display if the temperature inside exceeds 550F for more than 45 seconds. If this happens, your grill will shut off the auger and the fan to start the cool-down process. Once the temperature falls below 450F, the auger will run for 2 minutes to clear any embers from the auger tube. 
Power off the grill and let it rest and then clear any pellets from the fire pot. You’ll need to start the grill up yourself once you’re ready to fire it up again. This code is bad news and could signal the demise of your meat unless you act quickly to control the heat or remove the meat from the grill. 
Root causes of this kind of temperature surge include low-grade pellets that don’t burn evenly, a build-up of grease, ash, or sawdust that’s burning, or simply a faulty temperature probe giving an incorrect reading. 
The worst-case scenario is your temperature controller is malfunctioning. If you’ve eliminated the other possibilities, and you’re still getting this code, it may be time to contact the manufacturer for some help.

LEr 
This code indicates a “Low Temperature Error”, the exact opposite problem of HEr. If this code turns up, that’s because the temperature in the grill has dropped below 125F for more than 10 minutes. That’s a heck of a long time, but, relative to a multi-hour smoke, it’s not that big a deal. (You’re unlikely to see this error unless you’re trying to cook low and slow.) 
The grill will shut itself down, and then it’s up to you to restart. Clear the pellets from the fire pot and then begin the start-up sequence. 
There are several possible reasons you might get an LEr code: 
The simplest explanation is that you’ve run out of pellets, so there’s nothing to burn. 
It may be that the outside temperature is so cold your Traeger can’t get up to temperature. 
There may be debris that’s plugging your fire pot and preventing ventilation (you need oxygen for a fire). 
Maybe you’ve got a bad batch of pellets that’s full of sawdust. 
It could be a faulty probe 
The temperature controller could be on the blink. 
If it’s cold outside, try moving your grill somewhere that’s sheltered from the wind, or that’s in full sunshine to try and compensate. 

If you use your Traeger in the winter a lot, consider buying an insulation blanket; Traeger has them for many of their more popular models. You might even try pointing a space heater at it. Just don’t bring it indoors, unless suffocating on carbon monoxide sounds like a good time. 
The final issue to check is your “p” setting. “P” stands for pause, and it’s the length of time between pellet dumps into the fire pot from the auger. If you have a Traeger that’s a few years old, you can manually adjust this setting to one of three levels. Newer Traegers do not have this feature. 

ERR 
This is an easy one to diagnose, though it means you’re going to have to replace something. If this code pops up, it means your RTD probe needs replacing. Great — what’s that? 
RTD stands for “Resistance Temperature Detector,” and it’s just a fancy way of referring to the sensor probe that measures the ambient temperature inside the grill. 
Check the connection first to see if it’s just loose, but be prepared to order a new one. 

ER1 
Another code involving your temperature probe, this is a simple one. All that’s happened is you’ve got a loose connection. Try pushing the plug in or pulling it out entirely and plugging it back in again. 
If that doesn’t do it, something may need tightening, or there’s a defective or broken part inside. Call Traeger and see if they can troubleshoot the problem with you. 

ER2 
Well, this code sucks. If you see this nasty code, it means something is short-circuiting inside the controller. It could be to do with the RTD probe, or it may be an internal connection. Either way, you’ll want to call for assistance. 

There are how-to videos on YouTube showing you how to correct this error, but they all involve taking the controller apart and pulling out the circuit board. You’d want to be pretty confident in your electrical skills before you go this route!

SOURCE: foodfirefriends.com