It has been a while but I thought I'd update on my 93 940 wagon failing NJ emissions in high NOx. I posted in October when it failed the test.

http://www.brickboard.com/RWD/index.htm?id=1016851

It passed every item except NOx was high, at 1,226 versus 973 allowed.

About a month later, I was in Pepboys. I saw this product called GTP, "Guaranteed to Pass" on the shelf. It was, IIRC, less than $10. It guarantees that your car which failed the emissions test will pass if you use the product. I was skeptical but I thought for 10 bucks what did I have to lose? Even if it didn't pass I wasn't going to try to get my money back.

So I ask my younger son Russell who's a high school senior and driving the car everyday to pour a bottle into the gas tank. I did something more than what the instructions said. After mixing the product with a full tank, I told Russel to fill up with premium gas for the next tankful and take it to inspections.

The failed NOx index was 1,226. After treatment and a tankful of premium gas, the new number was 973, just at the limit.

Hurray!