The Simmer Control is an OEM component specifically designed for Bosch ranges. It regulates gas flow to provide the lowest possible flame setting needed for delicate cooking tasks. Precise control allows for uniform, attentive simmering. Symptoms of a bad simmer control include inconsistent or unadjustable flame heights on low settings. Cracks, damage, or wear of internal mechanisms over time can also cause unstable flame control. Causes of bad simmer control can be normal wear and tear issues like dirt buildup impeding mechanisms. Accidental impact or overheating leading to cracks are other causes for replacement. Symptoms of a bad simmer control include: Flames that surge or fluctuate below the lowest settings    Inability to adjust the flame down sufficiently low Burners that shut off or cause overflow flooding on low-heat   This OEM Bosch part is also compatible with Thermador and some Kenmore ranges. Replace for dependable, Fine-tuned low-heat performance.00645446 (AP4359679) replaces 00189009, 1550758, 189009, 645446, AH3479794, EA3479794, PS3479794, PS8730358.