Grill displays ERR4 and will not complete startup; temperature never rises above ambient.

Safety first: Unplug the grill before accessing wiring or the control panel.

• Locate the RTD probe: On Rösle pellet grills, the RTD (resistance temperature detector) is usually a small metal probe protruding into the cook chamber from the side wall.
• Inspect the probe: Check for physical damage, kinks, or cuts in the probe sheath and cable. If the probe is broken or heavily corroded, it should be replaced.
• Check connections: Remove the control panel cover to access the main board. Locate the RTD connector and ensure it is firmly seated and free of corrosion.
• Continuity test (if you have a meter): Disconnect the RTD from the board and measure resistance across the two leads. A typical RTD will show a finite resistance (often 100–2000 ohms depending on type). An open (infinite) reading indicates a failed probe.
• Replace RTD if faulty: Unscrew the old probe from the cook chamber wall, gently pull the cable through, and route the new Rösle-compatible RTD sensor along the same path, avoiding hot surfaces. Secure with the original hardware and reconnect to the board.
• Test operation: Plug in the grill and verify that the display now shows a realistic ambient temperature and no ERR4.