Problem with my friend's car

[Zeo]

My friend has a lincoln and it was around 120,000 miles. I suggested him to use STP complete concentrated fuel system cleaner (12oz) one. I actually bought one for him. After using the cleaner, the car has converter and engine light on problem. The car smell bad. He was not complaining that to me (well once). But I feel really bad. If I didn't gave him that STP, there wouldn't be the problem.
Any suggestions or what do you think why the STP ruin the car?
Thank you

 

[Zeo]

My friend's inspection ticket is going to expire next march. If the problem don't get fixed by that time, the car won't be passed the inspection. Does he need to replace the converter or something else? It smell really bad (like heavy gasoline smell when you in and around the car).
are there Any other additives that can help with this problem?

 

[clembrewer]

I would say to try the more well known fuel system cleaners = Redline SI-1, Gumout Regane, or Chevron Techron. Have him drive the snot out of the car while the cleaner is in the tank. Also, check or replace the spark plugs.

Take the car to Advance Auto or Autozone to find out what the code is.

The code most likely has nothing to do with the STP.

 

[Zeo]

For the engine light on, I don't know the problem.
But it is sure about the converter problem because he had his friend (mechanician) checked it already

 

[Drew99GT]

perhaps it ate the O2 sensor for the cat/emissions system.

 

[V1]

I vote for the Italian Tuneupnelis

 

[Zeo]

We are kinda sure the converter need to be replaced. As his another good friend (Mechanician) said so. But he is poor, the converter replacement may cost around 500 bucks. I am looking there is easy way and also unexpensive way to fix the problem. The car smell bad when the engine is on, especially if you stand at the rare of the car.
I don't think STP is bad product, but I am not sure why it caused the problem.
Thank you guys

 

[Shelby]

Maybe it's clogging your injector or Carb instead of cleaning it. I'm with Clem, run the tank low and put Chevron Techron in the next tank or two. If it's a Carb they are pretty easy to clean, just get a carb cleaner and follow the intructions. Smell the oil, if it smells like gas or real strong odor change it. Either change the oil and run mobil 1 in there, or maybe consider an Autorx treatment with cheap oil. If the gas smell is coming from the exhaust you should be alright, if the gas smell is coming from something else, don't get in the car.

 

[clembrewer]

Definately make sure that the fuel system isn't leaking! Get the code read and either google it or post it here. Something as simple as a misfire could let excess fuel into the exaust.

 

[Zeo]

I guess My friend hates additive after this case. LOL.
He had never used any additives before, this was the first time he used it because I recommended.
I guess I can hardly ask him to try any other additives. But I will try to tell him to use Chevron Techron. If I skrew up this time, he will LOVE me even better... lol