How to replace downstream O2 sensor in 2005 Hyundai Tucson

If your check engine light is on in your 2005 Hyundai Tucson, you may have an issue with one of your O2 sensors.  This is an easy thing to replace yourself if you’ve done any work on a car, and you can save a ton of money doing it yourself.  (A local dealership wants $250 to replace it; I did it for less than $60.)

The first thing you should do is have the code read and figure out which sensor is the one that needs replacement.  You can go to an auto parts store to have them read the code.  In my case, I had two codes:

  1. P0136 – O2 Sensor Circuit Bank 1 Sensor 2
  2. P0140 – O2 Sensor Circuit No Activity Detected Bank 1 Sensor 2

Here is a great post which will help you figure out the correct sensor location.

Bank 1 is the bank of cylinders on the firewall side.

Bank 2 is the bank of cylinders on the radiator side.

Sensor 1 is the O2 sensor before the cat.

Sensor 2 is the O2 sensor after the cat.

If you have a 4 cylinder engine like I do, it is simple.  There is no bank 2, only bank 1.  Sensor 1 is the upstream sensor under the exhaust manifold heat shield (you can see it just by popping your hood) and sensor 2 is the downstream sensor.  Here is how you replace the downstream (bank 1, sensor 2) on a 4 cylinder 2005 Hyundai Tucson.

Get a replacement sensor

You can certainly get the genuine Hyundai replacement from a dealership or online.  It is part number 39210-23750.  I found it online for $117 and had a local dealership match the price.  After I removed the old one I discovered that it is made by Bosch so I ended up getting it from my local Advance Auto Parts, part number 13461, for $60 (plus a $25 coupon I’m supposed to receive) using their weekly coupon code.  You can get it from Amazon for $40.  Since I already had my car jacked up and apart, I just went with the Advance Auto Parts purchase.

Genuine Hyundai replacement, old, and Bosch sensors.

Genuine Hyundai replacement, old, and Bosch sensors.

 

Old sensor, made by Bosch

Old sensor, made by Bosch

Get an O2 sensor socket

O2 sensors require a special socket that allows the wire to pass through it.  Auto Zone has a 3 piece O2 sensor socket set as one of their loaner tools.  There is no reason to buy one.  My car is 10 years old and has 136,000ish miles on it and this is the first time I’ve needed to replace a sensor.  The 3 sizes are actually quite handy.  I used the smallest crowfoot a couple weeks ago on a Subaru and it worked great in a really tight spot.  The crowfoot was starting to round off my O2 sensor (as you can see above) so I ended up using the full socket to break it loose and then switched to a crowfoot to loosen it the rest of the way.

Loaner O2 socket set from Auto Zone.

Loaner O2 socket set from Auto Zone.

Elevate the front of your Tucson

You should be able to do this without raising the front of your Tucson, but it will be much easier if you have a jack and jackstands or RhinoRamps.  I used my RhinoRamps.  Always remember to be safe.  Never use just a jack without jackstands, and I highly suggest chocking the rear wheels.

Elevate the front of your Tucson with a jack and jackstands or RhinoRamps.  Remember to chock your rear wheels.

Elevate the front of your Tucson with a jack and jackstands or RhinoRamps. Remember to chock your rear wheels.

Remove the old sensor

Find the sensor and disconnect its wire.  Here is a picture, facing the front of the car, with the threaded hole from which I removed the old sensor.

Bank 1, Sensor 2 (downstream) sensor location.

Bank 1, Sensor 2 (downstream) sensor location.

And a closeup.

Bank 1, Sensor 2 (downstream) sensor location closeup.

Bank 1, Sensor 2 (downstream) sensor location closeup.

Follow the wire from the sensor up to its plug.  Unclipping it is easier than with other cars.  Just squeeze the release with your finger, located on the radiator side by the red arrow, and pull.

Follow the sensor wire to the plug, behind the radiator fan.

Follow the sensor wire to the plug, behind the radiator fan.

Here is the male side after disconnecting the sensor wire.

Male side of O2 sensor plug after disconnecting sensor wire.

Male side of O2 sensor plug after disconnecting sensor wire.

And here is the female side of the plug on the sensor wire after disconnecting.

Female side of O2 sensor plug on the sensor wire.

Female side of O2 sensor plug on the sensor wire.

After disconnecting the wire, use an O2 sensor socket with a breaker bar (if you don’t have one, you can put a length of pipe on a socket wrench) and give a good hard pull (remember, lefty loosey righty tighty).  If your sensor is rusted badly like mine, you can spray some PB Blaster on the sensor and let it sit for a few minutes.  Some people suggest running your car for 15 minutes beforehand to warm it and some use a heating torch.  Just the PB Blaster worked for me though.  I started with a crowfoot because it is small and easy to work with, but it started to round off the sensor.  So I ended up cutting the sensor wire to get it out of the way and used the closed sensor socket to break the sensor loose and then used the crowfoot to loosen it the rest of the way.

Install new O2 sensor

The new O2 sensor should have anti-seize compound already on the threads.  The plastic cap in the first photo protects the anti-seize before you install it.  Be sure to remove that plastic cap and hand tighten the new sensor, being careful with the sensor end.  After hand tightening, use an O2 sensor socket/crowfoot and tighten it.  I’m usually a fan of using a torque wrench, but couldn’t find a Hyundai provided torque for this, so I went with 25 ft-lbs which was the torque for the O2 sensor I replaced on a Subaru a couple weeks ago.  Afterwards I noticed someone in this thread suggests 29.5 – 36.9 ft-lbs is the proper torque.

New O2 sensor hand tightened.

New O2 sensor hand tightened.

Crowfoot O2 wrench on new O2 sensor.

Crowfoot O2 wrench on new O2 sensor.

After you’ve tightened the new sensor with the O2 socket and a socket wrench, plug the sensor wire into the plug.  And you’re done!

New O2 sensor torqued and sensor wire plugged in.

New O2 sensor torqued and sensor wire plugged in.


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