See Engine Noise Diagnosis Videos

Proper engine noise diagnosis is a very important issue to address. In fact improper diagnosis can lead you on a wild goose chase. Note that I added 2 important videos of a true rod knock and a lifter tap at the bottom so you can be clear on the different sounds they make!

Here is an example of a mistake I made that taught me this valuable lesson. I had a double knock and believed the engine noise was a wrist pin. I removed the engine and disassemble it only to find out it was a camshaft thrust plate that came loose. I wasted day’s of work that was not needed. I was young when this happened but I think about it often when I hear engine noises.

Sometimes an engine malfunction will reveal itself first as an unusual noise. This can happen before the problem affects the actual performance. Some of these problems include badly worn piston rings or ring lands, loose wrist pins, worn main bearings or connecting rod bearings, and loose valve train components all produced telltale noises that are unique.

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The Gas Cap Code and DIY Check Engine Light Car Repairs

The gas cap code is a common diagnostic trouble code that might turn on your check engine light. I put together a video discussing a problem my neighbor had with his vehicle after they filled the fuel tank.

It is a common scenario that I see often. As you can see in the ladder diagram from the service manual, action step 1A is to check the fuel cap. Note: By popular demand I added a common evap system electrical diagram at the bottom as well.

You can see the short video and diagram below. But first I wanted to talk a little more about the gas cap code and the possible causes. On some automobiles it is known as the P0440 code.

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Check Engine Light Reset Procedures

The check engine light reset procedure can go down 2 paths. You can use a code scanner to retrieve and clear the codes, which is the proper method.

Or you could disconnect the battery and drain the memory holding capacitor in the computer to clear the check engine light that way. I will explain both for you, but I only recommend using a scan tool. Note I added an auto repair video explanation at the bottom.

If you disconnect the vehicle's battery this alone may not clear codes. Some manufacturers store voltage in a capacitor to hold the computer's memory. After the battery is disconnected you can hold down on the horn button to drain the small amount of electrical energy. This will definitely achieve the check engine light reset you were looking for. But there may also be some side effects to this procedure.

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Tips for Engine Light Diagnosis at Home

Basic check engine light diagnosis tips for driveway mechanics and automotive consumers. Determining which part or area of a computerized engine control system is defective requires having a thorough knowledge of how the system operates.

Then you can follow a logical troubleshooting procedure until the malfunction is uncovered. Thanks to the Government all late-model computerized engine control systems have on-board self diagnostic capabilities that can help point you in the right direction.

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Mazda Check Engine Light problems

This Mazda check engine light article pulls information from a technical service bulletin that was issued back in 2003. It applies specifically to 2001 through 2004 Mazda MPV multipurpose vehicles. This is of course Mazda’s term for minivan.

The bulletins specifically talks about a check engine light illuminated and storing a trouble code of P0706 which is a transmission trouble code. If you are interested in finding specific technical service bulletins for your exact year make and model of Mazda car or truck you can obtain these for a minimal expense alldata.com.

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How to Handle EGR Codes and Turn off Check Engine Lights

In my opinion EGR codes are quickly climbing the ladder of the most common causes of check engine light failures to be found on aging automobiles. This is often due to carbon clogging passageways or improper operation of the egr-valve. Common failed components are available below for purchase.

Several technical service bulletins for a wide variety of different makes and models have documented a few different problems associated with the EGR valve system. With some EGR problems you might set a diagnostic trouble code of PO401 or P0402.

You may also set trouble codes for an engine misfire, which would be in the PO300 range. It is also possible that your check engine light will not come on and you will just experience a noticeable problem such as rough engine idle or even engine stalling.

Exhaust gas recirculation valveA basic explanation of the EGR valve would probably help with the understanding of the diagnosis and repair of EGR codes. Exhaust gas recirculation is necessary for emissions purposes.

Unfortunately when it malfunctions it can actually push emission levels off the chart. The valve meters post combustion exhaust gases to be mixed with the intake fuel charge and this dilutes the mixture.

Allowing exhaust gas to flow into the combustion chamber reduces cylinder temperatures and therefore reduces the amount of nitrogen oxides produced at the tail pipes. Of course this system works hand in hand with other computer controlled on board emissions systems such as the catalytic converter and oxygen sensors to name a few.

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Common Check Engine Light Codes

Common check engine light codes are listed for you on this page at the bottom. This is not a complete or exhaustive list of every code that could be set in your computer's memory.

Instead, what I did was I went through the entire OBD II code list and picked out codes that I have seen set in the real auto repair world. I also included a short description of what that check engine light means so you do not have to hunt that down elsewhere.

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