Why is my Check Engine Light on?
Have you ever thought, “Why is my Check Engine Light on in my Volkswagen”? Today we saw an interesting case for why the light came on and the fix was pretty neat. We have all heard someone at some point tell us “Just check the gas cap”. While that may be true in some cases, the fact remains that we really only see that once in a while. The engine computer monitors every sensor and system in the engine at all times and when it sees anything out of the ordinary, it will turn the light on. This can be for any of a few hundred reasons. Today I’ll explain how we got to the bottom of a Check Engine Light in a customer’s Volkswagen.
“Why is my Volkswagen Check Engine Light On?”
A long time customer came in today. He was concerned because he had been driving to Rhode Island when his Check Engine Light came on suddenly. He called us and said that the light had come on but the car was running just fine. He made his way back and brought the car in. The first step was for one of our Master Technicians to first drive the vehicle to see if anything felt out of the ordinary. The only thing we noticed was a minor shake at idle and that the Check Engine Light was in fact on.
From there we use a Volkswagen Diagnostic Scan Tool to pull a code (a code is a sequence of numbers that lead us to a problem area in the engine, transmission, SRS system, or ABS system). The customer actually had 5 separate codes. All of the codes were related to the engine misfiring. From there we begin diagnosis. Vehicles need 3 things (more than that but these are the 3 main ones) to run. Air, Fuel, and Spark… In this case he had all 3. the next step was to measure compression (this is the internal pressure that the engine builds when running). It was slightly low. Next we performed a cylinder leak down test. We want to make sure that the engine is capable of holding the internal pressure that it builds.
Bingo!!! 3 of the 4 cylinders in this engine were leaking down. We looked into the cylinders with a bore scope (little camera that fits in tight places). This allowed us to see into the cylinders and intake. The technician noticed a great deal of carbon built up so we needed to remove the intake for further diagnosis.
Once the intake was removed we could see the top of the valves. “We found our problem!!!” The top of the valves were so caked up with carbon that the valves weren’t able to fully close. This was the cause of the cylinders leaking down and the cause of the misfire.
We cleaned the top of all of the intake valves by hand then used a vacuum to suck out the debris. Then a small machine called a “Walnut blaster” is installed and it blasts in finely crushed up walnut shells and vacuums them out to make the area brand new again. The intake is then reinstalled.
In total the diagnosis and repair took about 4-5 hours. We have seen this issue before but this was definitely the worst one. Since it was harder to clean, we had to take a little more time. Once the repair was finished, the car was cleaned and returned to the customer.
So if you’re wondering “Why is my Check Engine Light on in my Volkswagen“? Give us a call. Our trained Technicians have the experience to get you back on the road quickly without wasting any time replacing things that you don’t need. This will only save you time and money