SES for Oxygen Sensor
 

Hi to all!

The SES light on my 2003 Montero with 75,000 miles on it was intermittently coming on and off. I went to autoZone and the code was P0155.

P0155 defined as Heated Oxygen Sensor- Bank 2 Sensor 1 (H02S21) heater performance

Probable cause:
1. Open or short circuit condition
2. Poor electrical connection
3. Faulty H02S21 (Bank 2 Sensor 1)

There were 2 sensors (right and left) before the Cat, and 2 sensors (right and left) after the catalytic converter. I just want to make sure which one is which before I order the part.

The dealer quoted me $450.00 + tax parts and labor.

Is there a DIY on how to change the heated O2 sensor? Thank you!

AudsO2, I am a product specialist with Walker Products, a manufacturer and worldwide distributor of oxygen sensors. You can most certainly change out the sensor yourself. All that you should need is the new part and an oxygen sensor socket (22 mm). In some cases a 7/8 wrench will work. The link below will lead you to instructions on how to determine which sensor is Bank 2, Sensor 1 (pre-cat sensor). Make sure to get the direct fit part for your vehicle, as it will plug right in to the old connector. Follow the wire on your old sensor to find the connector. Should be a piece of cake. If you plan on ordering the part online, the parts finder on our homepage, or any other manufacturer’s homepage, can lead you to the right part number. Oxygen Sensor Catalog 2012

Hi WalkerTech,

Thank you so much for the reply!

Hi to all!
According to WalkerTech's Catalog, Bank 2 is located in the Driver's side and Bank 1 on the pasenger side. But when I check the part # it says only left and right. Is left side the same as bank 2 or driver side and right is bank 1 or passenger side?

AudsO2,

Left or right is determined in relation to the rear of the engine. The side of the engine on your left if you were standing at the back of the engine (the side with pulleys is always the front) contains the left sensor bank.

Check out this page of our 2012 O2 Catalog for visuals: Oxygen Sensor Catalog 2012

I hope this helps.