4AGE 20V Blacktop

transparent transparent

Diary of Swap
Cooling System



85/6 4AGE -> 4AGZE

transparent transparent



Air Intake Filter
Clutch Slave Cylinder
Clutch Master Cylinder
Coolant Flush
Distributor O-Rings
Exhaust Manifold
Fuel Filter

Fuel Pump Cut-off Switch

Ignition Timing
Oil Cooler Hoses
Oil Filter Adapter O-Rings
Oil Pan Gasket
Oxygen Sensor
Radiator Removal
Throttle Body Cleaning
TPS Adjustment
Water Pump


87+ Brake Upgrade
Caliper Rebuild-Front
Caliper Rebuild-Rear
Dust Shield Removal
Parking Brake Cable
SS Braided Brake Line


Ball Joint Replacement
Bushings Install - Front
Bushings Install - Rear
Steering Knuckle Removal
Struts/Springs - Front
Struts/Springs - Rear
Sway Bar End Links


87+ Antenna Replacement
Clear Turn Signals - Front
Clear Turn Signals - Rear
Door Hinges
Interior Door Triangles
Interior Headliner Painting
Interior Trim & Light Lens
Power Window Regulator
Rekeying Trunk Lock
Rust PM - Battery Bracket

Rust PM - Front Wheel Wells
Seats - MK3
Seats - Aftermarket
Shift Boot
SideMarker Mod
Sunroof Rattle
Wiper Switch


2006 Austin
2005 Austin
2005 Topeka NA2005
2004 Galveston
2004 Chattanooga SE2004
2003 Galveston
2002 Austin


Suspension Setup Pics
My MR2 Diary
Latest Pics of My MR2

Oxygen Sensor Replacement

Changing out the Oxygen Sensor is very simple repair. If your Check Engine Light illuminates intermittently while driving on the freeway, most likely it's an O2 sensor problem. Poor gas mileage could also mean a poorly functioning O2 sensor.

The replacement I used is a Bosch #12051, price was $49, and I purchased it from my local import auto parts store. FYI, this only works for the early model MR2s (85 - early 87) as they use a one wire sensor. Later years use a more expensive (and more effecient) 4-wire heated sensor.


1) The sensor is located at the bottom of the exhaust header, near where it joins with the downpipe. Two bolts hold the o2 sensor in place, 12mm I believe. Just undo these (see pics at very bottom for the location), and pull the old sensor out. Don't forget to remove the old washer that's in place.

2) Let the sensor hang free, and run your hand up the wire so you know where the plug is located. It's to the right of the distributor, see the circled area below. Unplug the connector from above, and remove the sensor.


Here's a comparison of the old versus the new:

A close up of the sensors:

Closeup of the plug:

And here's the washers (replacement sensor comes with the washer):



1) From the top of the vehicle, plug in the new sensor, and then feed it down through being careful as to how the wire is run around all the hoses down there.

2) Insert new washer, insert new sensor, tighten bolts. Voila! Now here are pics of the new sensor installed:

3) Before you start up the car, it's a good thing to reset the ECU. Do this by pulling the AM2 fuse for about 40 seconds. This fuse is located near the battery:


Home   •   Links  •   Email
(remove NOSPAM from resulting email address)
Thanks for Visiting! - Eric Southers

Disclaimer: This web page in no way replaces the MR2 repair manual. Follow what it says before me. The purpose of this page is to give you a better pictorial description of what to do. I cannot be held responsible for any mishaps caused by this web page.