Audi Audi S4 1991-1994 Emissions & Sensors Specifications

The emissions sensors for the 1991-1994 Audi S4 include oxygen sensors and air/fuel ratio sensors. These sensors are compatible with the 2.2L turbocharged inline-5 engine and are designed to work with the Bosch Motronic engine management system. The oxygen sensors are of the heated wire type, ensuring faster warm-up times and accurate readings. Compatibility is guaranteed for vehicles with the correct engine code and emissions configuration.

Emissions sensors should be inspected every 30,000 to 50,000 miles. Cleaning or replacing the sensors as needed is recommended. Use only Audi-approved cleaning solutions or replace with OEM or equivalent aftermarket sensors. Ensure the engine is tuned properly to avoid rich or lean fuel mixtures that can damage the sensors. Regularly check wiring and connections for corrosion or damage.

To replace an emissions sensor, start by purchasing the correct sensor for your vehicle. Locate the sensor near the exhaust manifold or downstream in the exhaust system. Disconnect the battery to prevent any accidental engine starts. Use a wrench to remove the old sensor, then install the new one by hand tightening. Connect the electrical connector and test the system using a scan tool. Ensure proper torque specifications are followed.

If the Check Engine Light illuminates, use a scan tool to retrieve fault codes related to emissions sensors. Common issues include faulty readings, contaminated sensors, or loose connections. Check for codes like P0130-P0135 for oxygen sensor faults. Inspect the sensor for physical damage or contamination from exhaust gases. Clean or replace the sensor as needed and clear the codes to test the repair.

To optimize performance, ensure the engine is properly tuned and fuel injectors are clean. Avoid using lower-quality fuels that can contaminate sensors. Regularly inspect and maintain the exhaust system to prevent leaks or blockages. Consider upgrading to high-performance sensors designed for turbocharged applications. Always follow Audi-recommended maintenance schedules to ensure sensor longevity and accuracy.