Ask the Auto Doctor: Fault code will explain check engine light

August 18, 2015 by JUNIOR DAMATO. Motor Matters /

Dear Doctor: I have a 2007 Chevy Colorado with 273,418 miles on it with the 2.9-liter engine. I have a check engine light that will not go out. I have had a diagnostic check and have had all sensors checked, replaced and serviced. The engine light comes back on within a couple hours of driving. Right now I keep driving with the light on. The truck runs great. What is happening to make light stay on?

Dear James: You did not mention the fault code in your truck. For the check engine light to come on there has to be a fault code stored in memory. You need to go to a professional shop that can diagnose the problem and report to you the fault code. I have heard this same complaint many times. I suggest you call Identifix for a shop that uses their service, so both the shop technician and the Identifix technician to get to the bottom of the problem.

Dear Doctor: My 1997 Jeep Cherokee has 137,000 miles. It will stall and "die" when I slow down to turn into a parking space, driveway or just go slow (10 mph). It is an intermittent problem, yet has happened five times now. I brought it in for service and was told that I needed a tune-up, which was done. The Jeep also has no pick up, like it's not getting enough gas. Any ideas?

Dear Barbara: Your Jeep has a very dependable 4.0-liter six-cylinder engine. An engine tune-up is a good idea if the spark plugs have not been replaced in 50,000 miles. The fuel filter is located in the gas tank and does not require replacement under normal conditions. When slowing down a couple of items need to looked at: make sure the EGR valve is closing properly, also check if the transmission torque converter is unlocking, check that the throttle body does not have a lot of carbon build-up.

Dear Doctor: I purchased a 2003 Mercedes Benz E320 three years ago with 57,000 miles on it. The car is great, except for an intermittent transmission problem. When driving very slowly, such as in a parking lot or slow traffic, the transmission seems to lock-up when going into second gear. The car then surges and bucks vigorously. This only happens when very little acceleration is applied. What do you think it could be?

Dear Tom: My first thought is to check the transmission fluid level, as well as the condition of the fluid. There is a special procedure and you have to use for Mercedes-Benz transmission fluid. You may what to start with a fluid and filter change to begin with.

Dear Doctor: I have a 2011 Toyota Camry with the six-cylinder engine. At 55,000 miles I replaced the original Michelin tires with Continental tires, based on what I read about good traction, low noise and wear. Since putting new tires on, I get a front end vibration between 70 and 80 mph. I have had the tires re-balanced with the latest laser balancing system. I've had a dealer wheel alignment. The tires have been rotated around but the results are the same vibration. I did not have this with the original tires. Any suggestions?

Dear Sam: Because you did not have the vibration with the Michelin tires but have the vibration with the Continental tires, something happened with either the installation process of the tires, such as bending a rim. Some brand tire tread designs are not compatible with some vehicles. An alignment will not cause the vibration you are complaining about. I suggest you go back to the tire shop that installed your tires and have them replace them with the same Michelin tires that you had originally had on the car.

Dear Doctor: I am purchasing a new Subaru Outback and was wondering if there is something that can be done to prevent the headlights from oxidizing, as I keep my cars a long time. Is there some type of cover or product that will protect and keep the lenses clear? Your comments would be appreciated. I'm a big fan of your column.

Dear Ron: The number one way to prevent plastic headlight oxidation is a simple coat of wax every couple of months. You can also simply apply a coating of Pledge, just like you would spray your furniture. The Pledge can also be used on all the plastic and vinyl on the interior for added protection and shine.

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