Where is the oxygen sensor on a 2000 Toyota Echo?
There are two oxygen sensors on a 2000 Toyota Echo: an upstream (pre-cat) sensor located before the catalytic converter and a downstream (post-cat) sensor located after it.
The following guide outlines where these sensors typically sit on a 2000 Echo, how to identify them, and what you can expect when inspecting or replacing them.
Locations of the oxygen sensors
Upstream oxygen sensor (pre-cat)
Common upstream sensor locations and how to recognize them are listed below.
- Threaded into the exhaust pipe just before the catalytic converter, often on the front section of the exhaust between the exhaust manifold and the cat.
- Wiring harness typically runs upward toward the engine bay, ending in a 4‑wire connector that plugs into the sensor.
- On many Echo models, you’ll find it mounted on or just behind the exhaust manifold area or on the pipe leading to the catalytic converter.
- The sensor itself is a small metal can with a four‑wire cable; the connector is usually located in a position easy to reach from beneath the vehicle or from the engine side.
In summary, the upstream sensor is placed in the exhaust stream before the catalytic converter, usually on the front portion of the exhaust pipe near the engine.
Downstream oxygen sensor (post-cat)
Details for the post‑cat sensor are outlined below.
- Threaded into the exhaust pipe after the catalytic converter, typically on the pipe just beyond the cat or a short distance downstream.
- Its wiring harness runs along the exhaust system toward the rear of the vehicle, ending in a 4‑wire connector.
- Access is usually from underneath the car; in some configurations you may be able to reach it from the engine side, depending on trim and exhaust routing.
- Like the upstream sensor, it has a small metal body and a four‑wire cable connected to the engine control system.
In summary, the downstream sensor sits after the catalytic converter and is used to monitor the efficiency of the catalytic system.
Tips for locating and handling sensors
When you're looking for either sensor, start from the exhaust manifold area and follow the exhaust pipe toward the catalytic converter for the upstream unit. Then continue downstream past the catalytic converter to locate the downstream sensor. Always verify you’re working on the correct sensor by checking the wiring harness and connector type, and ensure the engine is cool before handling electrical components.
Summary
The 2000 Toyota Echo typically has two oxygen sensors: the upstream (pre-cat) sensor located on the exhaust pipe before the catalytic converter, and the downstream (post-cat) sensor located after the catalytic converter. Identifying them involves tracing the exhaust path from the engine toward the rear of the vehicle and looking for 4‑wire sensors with connectors routed toward the engine bay or undercarriage. Proper identification helps with inspection, diagnosis, and replacement.
