General Motors GM Genuine Parts 213-1698 Heated Oxygen Sensor

Worked great. Easy to install once I got the old one out. That was a pain in the toosh. Solved my check engine light code.

Perfect fit for TrailBlazer with Vortec 4.2L engine. This got rid of my Check Engine Light with code P0420! This allowed me to pass emissions and now I don’t have to re-test for 2 years. Before blaming your catalytic converters, give this a try! It comes with anti-seizure already on the thread. Note this is for upstream sensor, easier if you remove your air filter box.

It came precoated with anti-seize on the threads, which was nice

I didn't have an O2 related SES (check engine light) but my Envoy would hesitate and mpgs had dropped. Replaced the old upstream O2 and performance is much improved. I'll watch the mpgs for a month or two and report more later.Update 8/5/2013 - No huge change to mpg after 2 tanks...+1 city to 15, +1.5 highway to 20.5, but every little bit helps.

Seems to be working fine so far. The old one was a pain to remove. Some people suggest using PB Blaster to loosen it up. I agree. All I had was elbow grease and a breaker bar. It worked, but expect this 10 minute job to take about 30.

I planned on installing the O2 sensor in my vehicle today. I took off work so I could and was excited to see the Amazon person arrive before 9am!!!When I opened the ACDelco box I was immediately let down. The O2 sensor’s plug showed traces of anti-seize. The O2 sensor itself had anti seize on the threads, and also on the element of the O2 sensor which is a big No-No. O2 sensors shouldn’t have anything on the element, not even natural oils from your hands.With the threads coated with anti seize and the Sensor itself, I didn’t want to take the chance of installing a part that’s most likely going to fail prematurely and which may have been installed and returned by someone else.Really let down, especially with the part coming from the manufacturer.Refund and purchase a different brand (Denso) locally.

Fit perfectly, easy install. Works like the original, mostly because it's just like the original. Wait, they are the same part number. Imagine that.

When I opened the package it was obvious that the product had been installed previously. There were scuff marks and grease residue on the connector plug, and the threads were full of dirty grease. I had to use the part anyway, because it was a replacement for an incorrect part received previously.