First of all, greetings. I'm new here.

I've got a 2006 Chevy Trailblazer LS with the 4.2l I6 motor, that just turned over 165,000 miles.

I've got a check engine light that comes on, code reads fuel injector cylinder #1 (first from front of motor, right?).

It seems to be very iffy. For example, I just changed the oil sensor (sending unit/switch) and after disconnecting
the battery, it took like 2-3 weeks before the check engine light comes on again. This is typical. I tried running
seafoam through the gas tank a couple of times (and I do it normally with every oil change), but that didn't seem
to make a difference.

So I've watched a few Youtube video's on how to change the fuel injectors and while a fairly extensive job, I did
not see anything that I couldn't do or needed super-specialized tools.

The local Chevy dealer people say I need to run a complete/deep computer scan rather than just relying on the
"quick" scan from places like Advance Auto parts.

So should I do that? If I do and it shows the same thing, can anyone recommend a good brand of fuel injector to
get? The A/C Delco brand seems very expensive and there are some other brands that are considerably cheaper.

Also, if I do proceed with this, should I replace all 6 injectors since I'm in there?

Thanks everyone, much appreciated...

 

Yes, injector #1 is the one closest to the front of the engine, #6 is closest to the firewall. Regarding the cheap injectors: how many times do you want to do this job?
Ya gets what ya pays for!
As far as replacing them all, that's really a question only you can answer. You need to weigh the cost of 6 good quality injectors versus the time and effort it takes to do the job. That's something only you can decide.
I do agree that it would be wise to have a more comprehensive scan done by a reputable shop. I avoid the stealerships, they just want to sell you as many parts as possible. It could be something as simple as a wire making intermittent contact.
I always advise against disconnecting the battery without using some type of memory saver. The reason is the HVAC actuators have plastic gears and as those gears age they get brittle. When the battery is disconnected and then reconnected the HVAC actuators go through a full sweep reset to find their home position. This runs the risk of stripping the gears out. Replacing most of the actuators isn't a big job, but the recirculate actuator requires removing the entire dash to get at it!
Do an internet search for OBDII memory savers, and you'll see what I'm talking about. I use this one https://www.autozone.com/test-scan-a...ord/220034_0_0 with a jump/booster pack from Harbor Freight. Be aware though that the battery terminals are live when using the memory saver so make sure to wrap them up well to prevent unwanted fireworks!
To replace the injectors the valve cover and intake manifold have to come off, is that correct? If so I would suggest replacing the valve cover and intake manifold gasket. You can get them both for $30-40.
I just looked on Rock Auto Parts website, Given the available choices, if I were to replace all 6 I would probably go with the Standard Motor Products injectors. I've had pretty good success with SMP parts. There appear to only be 3 AC/Delco injectors available. Delphi is a pretty good brand as well. They are an OEM supplier of electrical parts to GM. Stay away (FAR away!) from the cheap injectors and the re-manufactured injectors. Unless you really like doing this type of work. Then, knock yourself out!
I would first get it diagnosed by a reputable shop, though. You will pay for an hour or two of labor, but it may reveal that this is something simple, like a broken wire.
Good luck with it! I used to have a friend that lived in Lexington. That's a nice area down there!

 

Exactly what OBDII code are you seeing?

Like flyboy2610 said, cheap parts (not less-expensive quality parts) will cause you more grief in the long run and waste your time and money. Get NEW injectors branded/manufactured by Delphi, ACDelco, Standard Motor Products (non T series), BWD (non P series) or NAPA Echlin. Stay away from the white box, generic specials from ebay & amazon unless you insist on performing the work over and over again.

Diagnose first rather than dumping a bunch of money into parts that may be unnecessary.

Good Luck!

 

I'd strongly suggest a fuel injection cleaner, like Chevron Techron Complete, before you change injectors..