Locking gas cap

One of the most common OBD two codes would be for the evaporative emissions system. These codes were designed by the manufacturer and mandated by clean air laws.

Basically this is that the fuel system on every automobile must be completely sealed. No longer are you allowed to vent fuel vapor into the atmosphere.

This means that a storage and burning system is necessary to properly handle the naturally occurring fuel vaporization process.

Depending on the year make and model of the vehicle the codes set will usually be in the P0400 range. These codes when set will help you determine what the problem with the system may be.

When the fuel vapor system is determined to be leaking the severity of the leak is measured. Individual codes may set for a small leak, a medium-sized leak, or even a large fuel vapor leak.

Also in the P0400 range of codes will be specific codes for the canister and purge valve functions of the evaporation emissions system. All of the failures in the P0400 range could be considered common OBD codes. Again depending on the year make and model of the vehicle. But I have seen failures in all parts of the evap at one time or another.

OBD two evap systems leaks

OBD two monitors the evaporative system by testing the ability of the fuel tank to hold pressure as well as purging the system to vent petroleum fumes from the charcoal canister storage device. The most common way that this pressure test is deployed is with a small pump.

In this type of system the powertrain control module tests the evaporative emissions system by energizing the pump. As pressure builds the cycling rate of the pump decreases. If there is no leakage in the system the pressure builds until the pump shuts off.

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If there is a leak pressure does not build up and the pump continues to run until the test cycle is completed. If no leaks are detected by this test cycle the powertrain control module will move on and test the purge cycle.

Some systems have purge flow sensors between the solenoid and the intake manifold. In this case the PCM monitors the signal from the sensor once per drive cycle to determine if there is vapor flow at the proper levels into the intake manifold.

Note that on some GM vehicles enhanced monitors can detect leaks and restrictions in the system as well.

In these types of enhanced systems a poor sealing fuel cap or one that is missing is capable of turning on the check engine light.

The common gas cap obd two code

I’ve put together a video that discusses these common OBD two codes. Since the fuel cap is often removed for re-fueling this has become known as the weakest link in the system. Even if the gas cap is properly reinstalled the sealing ring between the cap And the filler neck can become nicked or worn over time. This often shows up as an Evap system code for a small fuel vapor leak.

Gas Cap Code Video

Also keep in mind when you’re vehicle sets the gas cap Code the check engine light will remain on even if the problem is intermittent. It is necessary after the repair is completed to clear the codes and retest the system.

For the latest posts and auto repair information this next link takes back to the home page from Common OBD two codes.

Solutions for check engine lights

Auto Mechanic

This was an auto repair information blog when I started it two years ago. Things stayed on topic, but changed a little when gas prices started to climb in early 2008. This is also when I purchased the water 4 gas systems and decided to share the details of my project with visitors. In today’s post I wanted to return to the original reason I started this blog. And that was to supply auto repair information for people that like to fix their own cars.

After fielding many questions over the last couple years on my car repair help page I have noticed one very common piece of advice that I continue to dispense. It also happens to be the first step in almost all of my automotive diagnosis procedures that I personally use. And this is the visual inspection. It is very common that I will uncover the cause of the car problem by simply performing a thorough visual inspection.

Auto repair visual inspections

I’m going to provide some examples of what to look for, and some of the most common things that I have found. It would seem that a visual inspection during these winter months are more important then in the summer. But regardless, I perform this procedure as a quick first step in automotive diagnosis no matter what the weather is like.

My first example actually happened yesterday and got me thinking about how I should share this with website visitors. I was working on a 2006 Chevrolet 3500 series van. The driver’s complaint was the check engine light was on.

I scanned the vehicle and found a map sensor code. The first thing I did was perform a visual inspection of the map sensor, the connector and its wiring harness. The first thing I noticed was little black chips of plastic that were laying on the intake manifold. These were obviously pieces from the conduit that protects the map sensor wiring harness.

I followed the harness back and found a spot where a rodent had chewed through not only the protective conduit, but also completely through the ground wire for the map sensor. There was no need for any scientific check engine light diagnosis because it turned out just to be a quick repair of a single wire.

Auto repair diagnosis

Another example of diy car repair diagnosis. My nephew called me from up north and said that he had an ABS light on. I live in Florida now, so I was not able to work on his vehicle. But I did notice in the news that they had recently gone through an ice and snowstorm. So I walked him through some simple steps to do a visual inspection on his own car.

I explained to him where the wheel speed sensors and wiring harnesses were located. When he poked his head around the wheel, he noticed a 15-pound ice burg was stuck and pulling on the wiring harness to his left front wheel speed sensor. Since my nephew is not very mechanically inclined, he was forced to take it in for repair.

But he was armed with the information to provide the service center that saved him Diagnostic time, and also the down time of his vehicle. The weight from the ice and snow that collected on the wiring harness broke the wires where they attach to the sensor head.

Auto repair safety

My nephew would have liked to continue to drive around with the ABS light on as opposed to spending the money on car repairs. In fact, I had to talk to his mother to force the repair to be completed. Antilock brake systems are a fantastic safety feature. During winter weather with ice and snow a properly operating ABS system may save your life or at least prevent damage to your vehicle or other drivers.

In closing I would recommend that when ever you have a warning light on your dash fix it. Either using do it yourself auto repair techniques or a car repair shop. And take a few minutes to perform a thorough visual inspection that is related to your problem. External damage by rodents and road debris can be highly visible and solve your car problems.

Ford’s top-selling F 150 will also have this new system, which was unveiled at the North American international auto show. It will be in your local showrooms and ford dealerships this fall. This new feature is also coming to the 2009 crossover vehicle the Lincoln MKS luxury sedan.

This new feature may not cause people to buy the trucks, but it is something that they will appreciate every time you fill up. The quick fueling system that was inspired by Ford’s NASCAR racing experience first appeared on the 2003 Ford GT sports car with rave reviews. Now every body can feel like the refueling chief on a race car pit crew.

How do you fill a fuel tank without a gas cap?

The race car inspired system has two small spring-loaded tabs that pull back a flap inside the fuel filler neck as the fuel-pumping nozzle hits them. When the nozzle is pulled out a flap closes and seals the fuel filler neck automatically. Besides the convenience factor of the cap less system, there are some environmental benefits as well. The quick opening and then re-closing of the fuel filler neck allows a reduction in the escape of gasoline vapors, which is bad for the ozone and the environment.

This gas cap less fuel filling system ends another common problem that occurs when a gas cap is not screwed on tightly enough. The dreaded check engine light that appears on the dashboard because of a fuel vapor leak will be a thing of the past. The integrity or the ability of the fuel system to hold pressure is tested by the vehicles PCM on every startup in case you where wondering.

If the you are further curious about things that turn on the service engine light you can visit my updated page about common causes of the check engine light. Also note that these are things you can fix yourself.

She was driving and her check engine light came on. She called me in a panic. I told her to take it to a chain store and hope for the best but to ask for the old parts back.

The shop said the vehicle needed an o2 sensor and my sister confirmed the light was out and received the old part.

When she got back in town I asked to see her old part, it was not an o2 sensor but an egr valve off of a large diesel engine. Definitely not from her little economy car gas engine.

When I looked under her car the old original o2 sensor was still in the exhaust stream.

To make a long story short the shop just cleared the check engine light and let her go after confirming with her she was heading back to her home state.
Two things to learn from this. One if you have out of state tags tell the shop you just moved to the state your in and have not changed your tags yet.

The shop knows that if you are a transient customer that they will never see you again and can give you the royal screw over with no problems.

The second lesson is if you ask for the old parts back know what the part looks like.

Have the shop show you the old part on the car before they remove it so you can confirm it is the part quoted in the repair estimate.

Learning some basic automotive skills will make you feel more confident about going in for auto service. The service writer or service manager will instantly recognize this confidence.

A consumer that understands the vehicle and how the auto service business works is usually passed over when it comes time to apply the rip offs and scams.

For more information on check engine light diy diagnosis. For more info on protecting yourself from auto repair rip-offs.

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