Using my electronic device, I found that the cause of the CEL is PO150 02 sensor in
"Bank 2 - sensor 1"

How do I determine exactly which sensor this is on the ML 320- in order to replace it properly??

Also, do I really need a special tool to remove the sensor or can I do it with the proper socket??

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Ben Harrison Carter
1999 Mercedes ML320 87K
1992 Mercedes 300CE 89K
1995 Corvette 29K -- Sold Dec 09
1989 Mercedes 420SEL 99K -- (Sold 4/08)
1968 Mercedes 230S (106K) (Sold 9/06))
1976 Mercedes 450SEL 130K (Just sold - 06)
1961 Mercedes 220Sb (sold years ago)

Bank 2, so cylinders 4,5, and 6

Sensor 1, so the upstream, or pre-cat sensor

A normal wrench will usually fit (22mm or 7/8"), sockets have a hard time dealing with the wiring coming out of the sensor. You can jam one on for removal of a bad sensor, but you wouldn't want to do that with a new sensor.

MV

before removing said sensor which is located on the driverside of the car before the cat - have it tested for signal.

I say this because if you have an exhaust leak near it the sensor code will be set.

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2012 BMW X5 (Beef + Granite suspension model)

1995 E300D - The original humming machine (consumed by Flood 2017)
2000 E320 - The evolution (consumed by flood 2017)

O2 sensors require a special tool. Somewhat like a socket except there is a cut out portion to feed the connecting cable thru. You can often make due with a crows-foot style wrench. Without the right tool you risk damaging the cable during reinstallation. O2 sensors are a 100K mile service item.

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Good luck.






1998 E320 Wagon

Bank 2 is the driver's side.

I have not done this on an ML, but on the sedans a dedicated O2 socket is required, unless you are going to drop the exhaust. As noted, it is deeper than a normal deep socket and has a cutout on the side so you don't damage the wire. You can get one at any auto parts store or online, of course.

Good luck.