Check Engine Light

[roy]

We recently purchased a 2004 Sun Voyager 8378 with the 8.1L engine. The unit had 43,000 miles on it and our first trip out was an 800 mile round trip. The engine ran fine with the only problem being the fuel mileage could have been better. Two weeks later we were going to take it out for a weekend stay at the State park but when the engine was started the check engine light can on and the engine was running very rough and at a very low rpm. All gauges are at the normal level. Any ideas where to start with out taking it into the shop?

[38Chevy454]

Plug a scan tool into the diagnostic plug. Usually on underside of dash, about 3/4 inch wide x 1.5 inch length plug. You can get it done at several auto parts stores for free. Or just buy the tool and do it yourself, $100 or less for a scan tool.

Now, the scan tool will just tell you what the computer has stored as the trouble code, it sensed something that was out of normal limits. It does not tell you what went wrong: broken sensor, bad electrical connection, or whatever. That is where you need some knowledge to figure out what the root cause of that code. Sometimes it is easy and you can put the replacement part to fix the problem. Other times it is not so obvious and you need the better scanning capability of the dealer or service dept tool. They have scanners that go deeper into the computer and read the levels and history. The cheap $100 tool is good, but only as an indicator.

Even if you don't fix it yourself, knowing what the trouble code is will help you understand the fix required and can get some idea of approx cost and effort to fix what is not working correctly. The scan tool can also reset the check engine light once you read the stored code(s).

[roy]

I removed the air intake tube from the maifold, started the engine and the light went out. Now I will have to back track the system to find the restriction. Thanks for the reply.