How Pellet Grills Work & How To Troubleshoot Components

How Pellet Grills Work

A pellet grill, also known as a pellet smoker, is a type of outdoor cooking equipment that uses wood pellets as fuel to create smoke and heat for cooking food. They can be used for many different types of cooking: smoking, grilling, baking, roasting, barbecuing, and more.

Pellet grills require an active power source such as home electricity, a portable power bank, or a car battery with a power inverter. This is necessary to power the electrical components inside the grill: controller, auger, fan, and igniter.

When starting a pellet grill, the airflow fan will spin steadily and the auger will rotate for a short period of time to feed pellets to the firepot. The hotrod heats up, and after a couple of minutes the pellets will start to smoke and burn. About 10-20 minutes later, the grill will be up to temperature and ready to start cooking. Total ignition time is usually 10-15 minutes for 200F and below, up to about 20-25 minutes for 500F. Ignition takes longer in colder weather.

The most common reason for performance issues with pellet grills are cleaning and maintenance. Even after just a few cooks, there will be noticeable food residue along the drip tray and grease channel which could catch flame if an ember falls in the wrong place. Over time creosote will also build up anywhere smoke touches inside the grill, especially the exhaust. As a general rule, before replacing any parts, it is best to clean any food and smoke residue from the interior and see if this improves the grill’s performance.

What Are The Parts In A Pellet Grill

Controller

How Does It Work?

The controller is “the brain” inside the grill - it gives instructions to all of the other electrical components, and maintains temps according to its programming. Older controllers have wider temp ranges up to 25 degrees from the set temperature, but newer controllers with better technology can usually maintain the set temp within 5 degrees.

Common Symptoms Of A Bad Controller

• Not turning on (nothing on screen, fuse still in good condition).
• Lines missing from numbers on the temp display.
• Auger runs continuously for 30s-2m then stops, and doesn't come back on until the grill is restarted.

How It’s Replaced

1. Unplug the grill to prevent risk of shock
2. Remove the screws on the controller, there should be either 2 or 4 holding it in place
3. Remove the controller from the grill. Sometimes it is easier to angle it sideways and push it through the hole, so it can come out underneath the hopper. This gives better access to the wiring for some grills.
4. Follow the wires from the back of the controller, and disconnect the white plastic MOLEX connectors. They may have locking clips.
5. Connect the MOLEX connectors to the new controller. The wires are often color coded, so make sure to connect them to the same colors or check your manual for a wiring diagram.
6. Reinstall the controller into its bracket, and reinsert the screws to hold it in place
7. Plug the grill back in, and you are ready to cook!

RTD Probe / Thermocouple

How Does It Work?

RTD Probes and Thermocouples have the same purpose: to read the internal temp of the grill. RTDs work by measuring the resistance as the temperature changes, and thermocouples measure the voltage as the temp changes. Functionally they are the same, but RTDs are more common in grills.

Common Symptoms Of A Bad RTD

• The most common indicator of a bad RTD Probe is when the temperature is inaccurate at startup. The temp on screen at startup should be within 10 F of the local temp in the shade. If the temperature difference is greater than 10 degrees, clean off the RTD of any residue and see if it reads accurately again. If not, replace the RTD Probe.
• Another common symptom of a bad RTD Probe is if the grill shuts down with an HEr error, without having a grill fire. This means the controller detected temps higher than 500 F, and it shuts down the grill as a safety precaution. Clean out the grill of any residue which could flare up, clean out the firepot of any unburned pellets, and try again. If the HEr error persists, replace the RTD Probe.
• Err / Er1 / Er2 errors indicate the RTD Probe has either come loose from the back of the controller, or it is not reporting a temperature for the controller. First you should remove the RTD wires from the back of the controller, clean them off, then reinsert the wires and try starting the grill again. If the error persists, replace the RTD Probe.

How It’s Replaced

1. Unplug the grill to prevent risk of shock Unscrew the 1-2 screws holding the RTD in place Unscrew the 2-4 screws holding the controller in place
2. Remove the RTD from the back of the controller. Usually the RTD has 2 wires going into a small box with 2 small flat-head screws. For some models, especially A-Smoke and Pit Boss, the RTD may have a black quick-detach connector.
3. Once the wires are detached, lightly pull on the RTD from inside the grill and take note of the route of the wire. You will need to route the new RTD wire along the same pathway. Some grills may require removing the hopper box to replace the RTD. If so, you will need to remove the bolts from inside the grill which hold the hopper box to the side.
4. With the new RTD in place and screwed down, pull the end of the wires gently from the hopper side to pull any slack wire from inside the grill.
5. Attach the new RTD wires to the back of the controller.
6. Put the controller back in place and tighten the screws. You are ready to go!

Igniter (Hot Rod)

How Does It Work?

The igniter is the initial source of heat to get the flame going. It runs for the first few minutes when you start the grill, then shuts down for the remainder of the cook. Some newer grills have a re-ignite function if it detects the flame may have gone out, but for most grills you will need to restart the grill.

Any time you suspect the igniter may be the reason for a delayed ignition or flame out, it is essential to clean out the fire pot of any pellets before you start the grill again. If you restart the grill and it already has pellets in the fire pot, it could lead to a hopper fire or a “lid burp”. A lid burp occurs when there is too much fuel inside the fire pot and not enough oxygen for it to burn. The pressure inside can push the lid open slightly, at which point air rushes in, and the lid “burps” open violently - it can even sound like a small explosion. Not only can it cause damage to the grill and surroundings, it usually also ruins anything you may be cooking at the time.

Common Symptoms Of A Bad Igniter

• Slow or failed ignition If your grill fails to ignite or takes longer than usual, then the igniter could be at fault. Clean out the firepot and remove any burnt residue from the exposed part of the igniter, then try running the grill on ‘smoke’ again. If it starts to smoke, put the heat baffle and drip tray and grates back inside, then close the lid. Let the grill heat up to temp, and you should be ready to start cooking again.
• If the grill still fails to ignite after doing the above steps, you may need to replace the igniter.
• If all other components are working properly except for the igniter, then you could run the grill by manually igniting the flame. It is not recommended to use firestarter fluid if you are doing a manual ignition.
• Not Maintaining Set Temperature: There is a misconception that the igniter has a role to play in maintaining the set temp, as some brands use the phrase ‘Hot Rod’ to mean the igniter. However, for most grills, the igniter only serves to ignite the grill at startup, and after the flame is burning the hot rod will shut off for the remainder of the cook.

How It’s Replaced

1. Unplug the grill, and remove the lower grate, drip tray, and heat baffle Underneath the hopper.
2. Access the bundle of wires coming from the back of the controller and disconnect the purple & white molex connector.
3. Tape the new igniter to the connector for the old igniter. You may need to cut some zip ties to give you extra slack to work with.
4. Unscrew the 4 screws holding the fire pot Lift the fire pot at a 45° angle, and pull it out so you can remove the igniter. Usually there is a set screw holding the igniter onto the fire pot.
5. Pull the old igniter gently, until the new hot rod comes out through the fire pot area.
6. Remove the tape, clean off any adhesive residue from the new igniter, and discard the old igniter.
7. Mount the new igniter to the fire pot, reinstall the firepot and its screws underneath the hopper, pull gently on the igniter wires to pull out any slack.
8. Reconnect the molex connectors. Your now ready to grill!

Auger Motor

How Does It Work?

Auger motors receive commands from the controller to turn the auger shaft, feeding pellets from the hopper into the fire pot. They turn at a fixed speed, so the feed rate is controlled by turning the motor on and off at set intervals. For example, on ‘smoke’ most Traeger grills will turn the auger for 15 seconds then turn it off for about 60 seconds. Auger motors often have a small fan on the back to indicate when the auger should be turning. This fan is for troubleshooting purposes and the motor will operate fine without it.

Common Symptoms Of A Bad Auger Motor

• Motor fan is turning but the auger is not turning.
• Clicking, ticking, or squealing sounds coming from the motor.
• Auger ‘hesitates’ while it is turning, but does not stop completely

How It’s Replaced (may be different for some manufacturers)

1. Unplug the grill from the power source
2. Remove the slotted panel from underneath the hopper. There will be 4 or 6 screws holding it in place. Some grills have an access panel on the side of the hopper to help with removing the auger motor. If yours does have this access panel, you can skip to step 7.
3. Empty the pellets out of the hopper box, as we will need to remove the hopper shell.
4. Remove the screws holding the control panel, then push the control panel into the hopper box so it comes out underneath.
5. Locate the 4 screws (sometimes more) holding the hopper box to the grill. Remove these screws. When removing the final screw, you will need to support the weight of the hopper box or it may fall.
6. Remove the 4 screws holding the auger motor to the grill frame, then remove the shear pin to separate the motor from the auger shaft.
7. Install the new motor, making sure to rotate the auger shaft so the holes line up for the shear pin.
8. Before reassembling the grill, it is recommended to do a test run of the grill to make sure the new auger motor is working properly. You do not need to add pellets for this test run. Be careful not to short-circuit the control panel while the grill is plugged in.
9. Unplug again after the test is complete. Reinstall the hopper box Route the control panel through the hole and re-mount it.
10. Reinstall the slotted panel underneath the hopper. You're up and grilling!

Auger Shaft

How Does It Work?

The auger shaft in a pellet stove is the spiral piece responsible for transferring the pellets from the storage hopper into the combustion chamber. It rotates to push or feed the pellets forward, ensuring a consistent supply of fuel for the stove to burn and maintain heat.

Common Symptoms Of A Bad Auger Shaft

• Grinding or snapping noises during grill operation.
• Flame out or temps running cool.
• Auger jammed or not feeding pellets. If the auger motor continues to push the auger shaft when it is jammed, it could bend the shaft and prevent it from rotating.

How It’s Replaced

1. Ensure the grill is cool, with no flame or embers in the firepot.
2. Follow the above steps 1-7 for removing the auger motor.
3. Some grills have an auger bushing between the motor and the auger shaft. If present, unscrew the screw holding this bushing in place.
4. Pull the auger shaft out. It may be helpful to use a screwdriver as a handle and lever, by putting it through the hole where the shear pin goes.
5. Rotate the shaft counterclockwise if there is difficulty sliding it out. Note: if there was an auger jam, you should clear out any pellets which may be stuck inside the auger tube or stuck to the auger shaft. Optional: roll the auger shaft across a flat surface, noting whether it wobbles or rolls smoothly. If it does wobble, this suggests the auger is bent and should be replaced.
6. Reinstall the cleaned auger shaft or install a new auger shaft. Put the auger bushing in place and secure it with the screw.
7. Rotate the auger on its axis, ensuring it can rotate 360 degrees without becoming stuck again.
8. Follow the above steps 8-12 to re-mount the hopper.
9. Re-prime the auger tube with pellets. This process can be different for different grills. Check your Owner’s Manual for instructions.

Shear Pin

The shear pin holds the auger motor and auger shaft together. Sometimes they may break during an auger jam, as a preventative measure to protect the auger motor from damaging itself.

Heat Baffle

The heat baffle sits above the firepot, and diffuses the flame to the sides so it doesn’t go straight up. This helps to regulate the grill temp. The heat baffle also helps to prevent any flammable cooking residue (namely oils) from getting into the firepot and causing a flare up. Heat baffles will warp over time, this is okay as long as it remains intact. Rust will also occur, this is also okay as long as there are no holes rusted through.

Drip Tray

The drip tray sits under the cooking grates. It collects any drippings from the food, and is slanted to allow the drippings to flow towards the grease bucket. As with heat baffles, drip trays will warp and rust over time. If any holes develop, or if the warping causes drippings not to flow to the grease bucket, then the drip tray should be replaced.

Cooking Grates

This is where your food gets that lovely sear! Cast iron grill grates are preferable for searing, as they retain more heat than ceramic grates. Grates are often coated with ceramic to make them easier to clean, however this means you should not use abrasive cleaners such as steel wool or metal scrapers. Wood scrapers and a household degreaser will make quick work of most food residue, and will also help significantly with cleaning creosote buildup.

Meat Probes

Meat probes are an easy way to monitor your food temps during the cook. They can be tested for accuracy in 2 ways, either with an ice bath or a boiling water bath. Even when they are working properly, they can have up to a 5-degree margin of error. It is recommended to always double-check internal food temps with a kitchen meat thermometer to ensure your food is fully cooked.