How to Install an Oxygen Sensor in a 1999 Sienna

The oxygen sensor in your 1999 Toyota Sienna helps to optimize the fuel economy and power output of the Sienna's engine. The oxygen sensor gathers information in the exhaust and sends it to the Sienna's computer. Using this information, the computer adjusts the engine's combustion-chamber air-to-fuel ratio. But oxygen sensors eventually fail and must be replaced to keep your Sienna running at its best. Replacement oxygen sensors can be purchased from most auto parts stores. Replacement of the sensor is normally required after about 100,000 miles of regular driving.

Things You'll Need

• Socket wrench
• Deep well socket set

Instructions

1. Open the hood and unbolt the front of the heat shield that covers the exhaust manifold on the front of the 1999 Sienna's engine.

2. Pull the heat shield off.

3. Locate the oxygen sensor, which is on the exhaust manifold. It's a small, round, brass module with wires, or electrical leads, coming out of it. Unplug those wires.

4. Unbolt the oxygen sensor using a socket wrench and pull the oxygen sensor off the exhaust manifold.

5. Thread and tighten the new oxygen sensor using a socket wrench and socket set.

6. Reconnect the electrical leads and replace the heat shield.

References

• "Toyota Sienna Repair Manual 1998-2009 by Haynes"; Jay Storer, John H. Haynes; 2010