Service vehicle soon?

Service engine soon ? Do you mean SERVICE VEHICLE SOON Indicator
The amber SERVICE VEHICLE SOON indicator is an alert to the driver whenever there are specific current codes stored in the BCM or in the event of a loss of Class 2 serial data.

If your vehicle has a check engine light ,it doesn't have service engine soon .One or the other .

I don't know who told you that , a semi- clogged catalytic will cause a low power issue an maybe a couple of DTC'S diagnostic trouble codes P0420 - P0430 ,Has nothing to do with the alarm system ! Do you mean Service vehicle soon or SERVICE ENGINE SOON ?
SERVICE VEHICLE SOON
The IPC illuminates the SERVICE VEHICLE SOON indicator in the message center when the PCM or the BCM detects certain non-emissions related malfunctions. The IPC receives a class 2 message from the PCM or from the BCM requesting illumination. What problem are you having with alarm system ? If you have a starting issue it's the Anti-Theft system not alarm system . The alarm would go off if you vehicle was broke into . I don't know what shop you took it to but did you try a dealer ?

How to Diagnose Codes P0420 P0430

There are really too many things to list that can cause the service engine soon light to come on. I suggest you have your mechanic scan your vehicle to see what codes are present to cause the light to come on.

The service engine light will come on for a variety of reasons, and to say what caused it is just a wild guess over the internet. It could be as simple as the gas cap was loose. You need to have the code(s) retrieved to determine the reason. In some states your local Auto parts store will do that for you and some are free.

There could be a hundred causes for a check engine light. First step is to hook up a computer scan tool and see what codes the computer has. The next step depends on the codes.

normally when you get a service engine soon light it means something emmision related needs your attention. I recommend taking your vehicle to either an authorized dealer if you wish to pay or you can go to an AAMCO or an AUTOZONE for they supply this serice free of charge. Its called a OBD II scanner and if your vehicle is 96 and newer they can do it. Keep in mind if you live in California then AAMCO is your only option cause AUTOZONE in California is unable to supply this service. That scan will give you more information on what needs to be serviced. Good Luck

Need to have sombody with a scan tool scan your vehicle, which will give you a dtc (dianostic trouble code) and determine what is cause the service engine soon light to come on

The Service Engine Soon light is a notice from the vehicles on-board computer that a problem has been detected somewhere, and service is required. You can isolate the problem by having the "trouble code" displayed for you at an auto parts store for FREE to determine the exact problem, and possible causes. This should be done FIRST, so that you strategically approach the problem directly instead of spending unnecessary money "guessing or assuming". If you are trying to save a few bucks, you may want to invest in a Chilton's manual for you vehicle as well for step-by-step repair, and diagnostic info specifically for your vehicle. I hope this helps,...and good luck!!

I'm assuming you are talking about the "service engine soon" light. This light comes on when the PCM has detected a problem that affects vehicle emissions, may cause powertrain damage, or severely impacts driveability.

99 - 04 grand am.

I had the "service vehicle soon" light come twice with in 1 year. First the heald light bulbs were gone. Replaced the head light bulbs and after 2 starts the "service vehicle soon" light was gone.

The second time the DRL - #194 amber bulbs were gone. Replaced these and the "service vehicle soon" light was gone after 2 starts. The DRLs are housed in the headlamp housing, the tiny bulbs beside the head light.