HQRP® Knock Sensor compatible with Toyota 4Runner 1988 / 1989 / 1990 / 1991 3.0L V6 Toyota Celica 1988 / 1989 / 1990 / 1991 2.0L L4 Turbocharged Toyota Pickup 1988 / 1989 / 1990 / 1991 3.0L V6 Toyota MR2 / MR-2 1991 2.0L L4 Turbocharged HQRP Ignition Knock (Detonation) Sensor. This is a replacement part of the highest quality. A vehicle knock sensor is a sensor screwed into the engine's block or cylinder head. It allows the engine to run with the ignition timing advanced as far as possible. The automobile's computer continues to advance the vehicle's timing until the knock sensor detects knock or detonation. After that the sensor sends the computer a signal to adjust the timing. This ensures greater FUEL ECONOMY and MORE POWER to get the most from your engine! Compatible with following Vehicles: 1991 Toyota 4Runner 3.0L V6 1991 Toyota Celica 2.0L l4 Turbocharged 1991 Toyota MR2 / MR-2 2.0L l4 Turbocharged 1991 Toyota Pickup 3.0L V6 1990 Toyota 4Runner 3.0L V6 1990 Toyota Celica 2.0L l4 Turbocharged 1990 Toyota Pickup 3.0L V6 1989 Toyota 4Runner 3.0L V6 1989 Toyota Celica 2.0L l4 Turbocharged 1989 Toyota Celica 2.0L l4 1989 Toyota Pickup 3.0L V6 1988 Toyota 4Runner 3.0L V6 1988 Toyota Celica 2.0L l4 Turbocharged 1988 Toyota Celica 2.0L l4 1988 Toyota Pickup 3.0L V6 Compatible with following P/N: 89615-20010 / 89615 20010 / 8961520010 / KS-95 / KS95 / S8646 / 71-6747 / DKS541 / 5S2371.