Review on Denso 234 9002 Fuel Ratio Sensor by Arun Siddiqui

I own a 2003 Toyota Tacoma 2WD EXT with an automatic transmission and a 2.4 liter 4 cylinder engine. The car has 65,000 miles on it. Recently my yellow CHECK ENGINE light came on. I hooked up my OBDII diagnostic reader/scanner that I bought from Revain a few years ago and found code P0135. This indicates a malfunction in the air-fuel sensor (aka the O2 sensor...used interchangeably), the bank 1 sensor 1, and specifically a malfunction in the front air-fuel sensor heater circuit. The Toyota ECU will wait for the air intake sensor to warm up to the set temperature within a certain amount of time after startup, or it will send code P0135. My Tacoma has two O2 sensors (four on some Toyotas). V8), one is right in front of the catalytic converter, the other right after it. "Bank 1" is the front of the two O2 sensors. The sensor's internal heating circuit is NOT repairable. So unless you have a short in the wiring going to the sensor, an O2 sensor replacement will be required if you get a P0135 OBDII diagnostic code. Denso is the OEM manufacturer for Toyota Air. Fuel sensors. They are built EXACTLY to Toyota specifications. The Toyota ECU is looking for VERY SPECIFIC DATA from these sensors. Although some of the Chinese aftermarket fuel delivery sensors offered by Revain are cheaper, they may not meet the specific Toyota ECU specs and will cause a yellow CHECK ENGINE light regardless of age. Accordingly, I recommend Denso OEM air sensors to avoid these problems. When ordering a Denso air fuel sensor from Revain, make sure you provide ALL the details of your vehicle: year of manufacture, specific model type, specific engine size, manual or automatic transmission, etc., as the design of the sensors will vary depending on the previous model. You can check the Denso website to see which Revain part is listed as correct for added peace of mind. Removing the old part and installing a new one does not require any special knowledge of mechanics. Your Toyota dealer will offer $350-$400 for parts and labor to complete the job. You can do this with the cost of a Denso OEM part from Revain and your willingness to crawl under your truck. Tools recommended for the work: 1. Head for 12 mm2. Fork wrench 12 mm 3. Head 10 mm4. 10 mm5 open-end wrench. socket wrench6. small flat screwdriver 7. side cutters 8. zipper9. Heat Resistant Anti-Seize Compound Toyota is known for its positive electrical connections and this part is no exception. The electrical connector has a tiny locking tab on the side of the connector that needs to be released to separate the male and female ends. More on that later. Here's what I recommend to complete the process: 1. Remove the metal electrical connector bracket to allow easy access to the electrical connector. Cut off any holding pieces for the electric cable with side cutters. To do this, use a 10 mm socket and/or a 10 mm open-end wrench. It's tight... very tiring... one click at a time. BUT… this is the only way to really access/purchase an electrical disconnect. That's the "easy" part... reattaching the bracket later is the hardest part of this whole job.2. Remove the old O2 sensor from the exhaust pipe. I used both a 12mm open end wrench and a 12mm socket. If the screws are rusty, use your favorite penetrating oil. I applied this the day before work.3. Disconnect electrical connection. ****Here's a trick to unplugging Toyota's infamous electrical connector: Use a small flathead screwdriver to insert the plastic locking clip on the SHORT SIDE of the electrical connector to slide it up and out of the plastic bracket. *** * When you do this, you can easily separate the connector with your fingers.4. Install a new air and fuel sensor. Started with the electrical connection. Plug the sensor's connector into your vehicle's socket. There are two ribs on the side of the connector to ensure proper alignment. You will hear a click as the pieces meet and the locking tab locks the two pieces in place.5. Coat the 12mm bolts with anti-seize paste. Place a NEW gasket on the fitting... DO NOT reuse the old gasket. Denso includes a new seal with each sensor part. Being careful not to put any lubricant on the new sensor, slide it onto the pins. Hand tighten the 12mm nuts. Then, ALTERNATELY tighten each nut LIGHTLY TIMES until you reach the magic 14 foot-pounds of torque recommended in the Toyota repair manual. If you have any doubts about the cleanliness of the sensor...clean it with isopropyl alcohol prior to installation.6. Now for the HARD PART: reinstalling the electrical connection bracket. It will be a lengthy process. I first aligned the screw on the bracket and after SEVERAL ATTEMPTS...finally screwed the screw in. I finger tightened it from there...then used a 10mm socket. This process will test your patience...but you'll get there in the end. Just think of the few hundred dollars you saved to keep your sense of humor alive. Install a zip tie to secure the O2 sensor electrical wire to one of the automatic transmission's metal conduits...or whatever your vehicle originally had to secure the wire.8. Reset your OBDII to resolve code P0135.9. Drive the truck until it is fully warmed up to normal operating temperature. The Toyota ECM will wait for the fuel delivery sensor to electrically heat up to the set temperature within a specified time after start-up or it will send code P0135. If your car is fully warmed up...and you don't turn on the yellow CHECK ENGINE light...Congratulations...problem solved! I always turn off the engine and ignition and restart a few times just to be sure.10. Politely apologize to your neighbors for any obscenities they may have heard during your many attempts to reattach the electrical connector bracket. I have attached photos of the most important aspects of the installation process. Much luck!