My 2004 Chevy Astro Light (service engine) will not go off.... Is there a problem that I should be aware of? Short of having it diagnosed and the codes read at a shop? Perhaps an oxygen sensor? It has 150,000 Kms on it. Thanks John

This a very common problem.
A loose CMP sensor causing a variance in the sensor signal
Excessive free play in the timing chain and gear assembly
Incorrectly installed distributor - 1 tooth off in either advance or retard positions
A loose distributor rotor on the distributor shaft
A faulty crank position sensor

One of the sensors minimum has returned as faulty get the codes read to diagnose the problem

You have dash lights,service light & such on

Do you not know about checking for codes
when any dash light stays on?

No one can diagnose your vehicle over the internet

Check for codes

Use codes to diagnose &
component test the system with
the fault & make repair

Same thing you did on your last check
light with any vehicle

You need to get the fault codes read to determine where the problem is that set the SES light. Autozone will scan your car at no charge. At some point you will need to get a mechanic involved to further diagnose the codes.

When the check engine light is flashing, it indicates a serious condition. You need to have the car scanned for trouble codes and diagnosed, making guesses is going to waste money.

Hi, the 4.3 liters have an injection system on them that can leak and will show up as a misfire. it is common but elusive to find. you might consider taking the van to a repair shop to have the problem diagnosed and go on from there.

have system scanned to get trouble code

DO U HAVE A CHECK "ENGINE/SERVICE ENGINE SOON" LIGHT ON??

Look for wires hanging, near the tire area under the car. An ABS sensor wire may be broken or the sensor is damaged.
Getting the system scanned will tell you exactly what is going on.