Audi Audi S6 2018-present Emissions & Sensor Bolt Torque Specifications

Precise torque is critical to ensure a proper seal and electrical connection for emissions sensors. Over-tightening can damage the sensor or threads, leading to inaccurate readings or sensor failure. Under-tightening can result in exhaust leaks, which will impact emissions and trigger fault codes.

Overtightening can crush the sensor's gasket or damage the sensor housing itself, rendering it unusable. In more severe cases, you can strip the threads in the exhaust manifold or pipe, requiring costly repairs. You might experience inaccurate readings or no reading at all.

Undertightening will likely result in an exhaust leak, which will allow unmetered air and/or exhaust to escape. This will cause inaccurate sensor readings and can lead to check engine lights, poor performance, or even damage to the catalytic converter. A loose sensor may also vibrate and cause damage to the wiring or electrical connector.

Generally, it is *not recommended* to apply anti-seize or lubricant to the threads of most modern emissions sensors. They are often designed with a specific coating that provides sufficient sealing and prevents seizing. Applying anti-seize can alter the clamping force of the fastener and may result in inaccurate torque application, potentially leading to over- or under-tightening. Always follow the manufacturer’s specific recommendations or specifications.

Emissions sensors generally do not require frequent inspections unless a problem is suspected. However, they should be visually inspected for damage when performing other routine maintenance around the exhaust system or when encountering emissions related fault codes. Pay attention to the sensor's wiring, connector, and any visible signs of damage such as cracks or contamination. If your vehicle is showing emissions fault codes or is not passing smog tests, inspecting the sensors and related components should be part of the troubleshooting process.