jdmjunk

Main Heated Oxygen Sensor Signal (Fr)


When I look at the Header there are 2 O2 Sensors

Are they talking about the front or rear O2 sensor when it gives this code?

turbogs300

21 is the front sensor in the bank closest to the front of the car. You should replace them in sets for better performance as the older they get the slower they react.

johnee78

iTrader: (4)

So are you saying that the sensors dont have to be bad , but as they get older they dont work as efficiantly?? Would a CEL turn on if this was the case?? Im asking because my car is a 93 with 157,000 miles and Im wondering if I should change them out..

turbogs300

I don't believe the CEL will trigger unless there is a complete failure of the heater or the sensor in the 02 sensor. if you have 157thousand miles and they've never been replaced, I'd replace them. They usually only last or are designed to be replaced around 90 to 100 thousand miles, sometimes much less. If you pull them out more than likely they will be coated with carbon. Yes, as they get older they react less efficiently.

johnee78

iTrader: (4)

Thanks for the reply..Are they difficult to replace?Do I need to use factory or can I use aftermarket, like bosch for example??

turbogs300

They are usually very easy to replace, depending where you live. if you live in a climate that has alot of moisture or salt and moisture they can be difficult to remove, as they may get rusted into the exhaust. You'll need an 02 socket to remove and install the sensor, available at almost any autoparts store. There are different sizes so make sure you get the correct one for your vehicle. OEM is the best and will have the correct plug to plug into the OEM wiring. Aftermarket like bosch are universal and don't have any plugs, so you'll have to determine your wiring and the solder the old plug onto the new sensor, however they are usually about half price. Soldering can be a little harder as sensors use sranded metal wires that are not copper or copper coated. I used Bosch or borg warner on all my cars and have had no problems, some people prefer OEM.

johnee78

iTrader: (4)

Thanks for the reply again..I always like to run factory parts so I will probably go with the faftory O2 sensors..I live in florida so I am going to soak the bolts holding the sensors with PB blaster , hoping that it will help loosen them up..Ill keep you guys updated if I notice any differences between the old and new sensors..

turbogs300

An increase in MPG should be the biggest change you see

Lexus Dawg

Turbogs300, are they expensive to replace? My 95 is around 95K, maybe I should do the same. Who is a good source for the OEM?

turbogs300

There are 3 sensors total, unless you have a california vehicle then y0u'll have 4 total. They range from $60 for the universal to $90-$110, depending on which sensor you need. The only difference is the wire length. The universal will need to be soldered to your old o2 plug, so it's plug and play. Wire colors will be different, however it's easy to figure out which wires are which. The biggest improvement will be in MPG. You should reset the ECU once you've replaced the sensor or sensors.

02 Sensors

johnee78

iTrader: (4)

Do I have to change them all at once or can I change 1 at a time or as I get more money?? I want to start with the two pre-cat sensors and eventually change the 1 after the cat..

Lexus Dawg

Thanks for the info T!

johnee78

iTrader: (4)

Turbo, thanks for the link to the oxygensensors.com..I want your opinion on whether I should get the denso ones from the site or just get from the dealership??My price difference is only about $40 total..What do you suggest??

turbogs300

Denso makes very good o2 sensors, I would go with whatever is cheaper..

johnee78

iTrader: (4)

Thanks, I ordered the densos..Ill let you know how they are when I get them..