Check Engine Light / Diagnostic

Your car's internal computer is designed to alert you when there is a problem with your vehicle. Some items (like your brake pads) can be inspected during your regular maintenance services, but others would require hours of labor to inspect - it's just not worth your money to pay someone to do it. That's why the manufacturers use computers, to monitor those systems themselves. When your check engine light turns on, it's usually to tell you that there's a problem with your vehicle.

For a check engine light, the appropriate first step is always to check the concern and inspect further. The reason is that there can often be multiple problems that cause your computer to generate any given code, so the technician will need to evaluate the issue further in order to make an appropriate recommendation and limit the money you spend on unnecessary repairs.

The technician will generally start your check engine light diagnostic by scanning your vehicle's computer to read which fault codes are triggering the light. This will help them know where to look; after that, they can begin test driving, disassembly of the relevant area, testing the system (as necessary), referencing the technical service bulletins on your vehicle (a list of common issues and resolutions for vehicles like yours), and any other measures to try to identify the source of the issue further.

Depending on how many codes your vehicle has, the technician might be able to cover this issue in one diagnostic, or other times, multiple diagnostics will be necessary. Unfortunately, it's a diagnostic inspection - the technician needs time to figure out what's happening with your vehicle, so it's difficult to say how long it will take.

With diagnostics of this type, it is important to keep in mind the complexity of your vehicle's computer and associated systems. After every repair, we recommend rechecking the system, to see if the issue is fully fixed. What sometimes happens is that you will have two items that have broken simultaneously. After the first one is fixed, the second one becomes visible. However, the recommended repair usually does fix the issue for you!

Any noise diagnostic starts by replicating the noise. That means the technician is confident that they hear the same thing you do. The fact of the matter is that your car makes a lot of noises, so a good technician wants to make sure they're not spending your money trying to find a noise that you don't even hear! This may include test driving the vehicle, if you only hear it under certain criteria (like when you're driving on the freeway).

Once the noise has been identified, sometimes, the work is done (if there can only be one cause). More often, a bit of disassembly or testing time is necessary, but usually that is sufficient.

Unfortunately, everyone hears and describes noises a bit differently. And even if the technician did know the exact noise, they still might need additional time to pinpoint the exact cause.

That's easy! There are a few easy steps. First, ride along in your vehicle with the technician. This will help ensure they hear exactly what you do. Next, try to answer the questions below; they will help ensure the technician spends time in the right area, and makes an appropriate recommendation for you: How often do you notice the noise happening? For example, once per day, multiple times every day, or all the time?

What does the noise sound like? Is it a lower pitch grinding/groaning/growling noise, or a higher pitched squeaking/chirping/rattling noise?

Does the noise happen when you are driving, or while stationary? If driving, what speeds/road type do you most notice the noise on?

Are there any specific instructions we should give the mechanic to be able to duplicate the noise?

From the driver seat, where does it sound like the noise is coming from (front of car, back of car, left side, right side, etc)? Does it sound like it's coming from the inside or the outside of the vehicle?

Does the noise occur when the vehicle is cold, warming up, or at operating temperature?

Does the noise seem to be related to the outside temperature? For example, it only happens in the morning when it's cold, or in the daytime when it's hot outside?

Usually, a leak just develops through normal wear and tear. A small crack in a hose or a plastic connection can cause some of your fluid to leak out, and require replacement. Of course, sometimes the leak can develop from other factors. Examples would include an external factor damaging part of the system containing the fluid, or perhaps a mistake by someone who has worked on your car previously (it can happen, unfortunately, but it will be covered under the warranty!).

No! Your vehicle has a lot of fluids, so let's go through the different types of leaks you might hear: coolant leak, transmission fluid leak, differential leak, brake fluid leak, power steering leak, oil leak, transfer case leak, and fluid leak.

Thankfully, other than oil, most of those fluid leaks land on the ground, so you are able to catch the leak fairly early on in its life. Once you do, a technician is able to diagnose the problem more rapidly, since they can observe the leak and trace the relevant area. At Stress-Free Auto Care, we typically recommend taking about 30 minutes in order to diagnose the leak effectively.

If the leak doesn't get caught early, usually the case with oil, there is a chance that we won't be able to tell where it came from. The oil will get caked all over the engine, and the technician will need to steam clean the oil residue in order to remove it from the engine compartment. At this point, they can then insert a dye into your oil. If the leak is severe, the technician will then be able to determine the cause right on the spot. If it is smaller, you might actually need to drive your vehicle for a bit (there's no hard rule, but we can typically see anywhere from 50-300 miles) and let the oil work itself back out. At that point, you can come back in for a free recheck, and the technician can use the dye to locate the source of the leak.

Spark plugs are the small, but important engine components that receive high voltage electricity and create the spark that ignites the air/fuel mixture in each cylinder of the engine. Depending on the age of the vehicle and the style of its ignition system, each spark plug is connected directly to an ignition coil, or to a wire leading to the central coil/distributor that provides the voltage needed to create a spark. When an engine is running properly, a spark is produced once per engine cycle (once every two RPMs on a normal car's engine). The spark is produced by the electrodes at the end of the plug (shown below on the left) and then enters the cylinder to start combustion of the air and fuel present.

All spark plugs have the same basic design and function. There may be slight variations in plug length or size between vehicles. The main differences, though, lie in the style of the center electrode as well as the size of the electrode gap. These factors are specified by the manufacturer to optimize engine performance and efficiency. Diesel vehicles are one exception, in that they do not have spark plugs (the fuel is ignited by compression instead of spark).

For several reasons, spark plugs are a maintenance item on every vehicle and should be replaced at the intervals specified by manufacturer before they reach the point of failure. Over time, spark plugs become contaminated and fouled (primarily by carbon buildup, but sometimes by oil or fuel if an engine is not running well). The electrodes can also wear down, or the gap can become excessive. In some instances, the insulation portion of the spark plug can crack from age and heat and lead to misfires. Additionally, fluid leaks from the top area of the engine can make their way to the spark plugs and contaminate them.

Ideally, spark plugs will not pose a problem if they are replaced according to the manufacturer's schedule. However, spark plug issues can present themselves in the form of a slightly rough idle, decreased fuel efficiency, or even misfires and a check engine light. In extreme cases, a vehicle may have such worn or fouled spark plugs that it will not start.

If spark plugs are not replaced when they are due by the vehicle's maintenance schedule, the symptoms described above may begin to occur. As the rough running conditions and misfires worsen, one or more spark plugs may cease operation completely. When this happens, the fuel in that cylinder is not being used so it is exiting the engine into the exhaust, where it can damage the catalytic converters. By replacing spark plugs as a maintenance item before they fail, these issues can be minimized. If problems do arise, addressing them as soon as possible will help to ensure minimal damage to other parts of the vehicle.

If spark plugs are being serviced purely for maintenance, they are often the only component that needs to be replaced. However, on a car with higher mileage, it often makes sense to replace old ignition coils at the same time due to the overlap in labor. This helps to ensure that failure of these components is avoided, and prevents having to pay for labor to replace the coils when they do fail. If there are any engine problems that are damaging the spark plugs (excess fuel, or oil leaks, for example), they should be addressed to prevent further damage to the new spark plugs.

A fuel injector is the part of an engine's fuel delivery system that receives and sprays gasoline (or diesel) into the engine in the form of a high pressure mist as illustrated in the diagram below. Fuel injectors are controlled by the engine computer to optimize the amount of fuel as well as the timing of the fuel injection. There is one injector per cylinder that delivers fuel to the engine.

In a traditional fuel injector setup (primarily used from the late 1980s - 2010), the injector sprays fuel into the intake manifold, where it mixes with air before entering the combustion chamber where the mixture can be ignited.

In recent years, more manufacturers have made the switch to direct injection, a system in which the fuel injector sprays gas directly into the cylinder, instead of into the intake. This system allows for higher fuel efficiency and better emissions control as well as higher power output from smaller engines.

Fuel injectors are not wear items and can even last the life of the vehicle sometimes. However, as with every mechanical part, there are issues that can and do occur.

Fuel injectors can fail from contaminants (such as dirt, carbon buildup, or low-quality fuel) clogging the injector. Sometimes they can be cleaned, but they often require replacement. A fuel injector can leak due to aging of its rubber seals, or it can leak from cracks in the injector itself.

If the seals are the culprit, they can usually be replaced on their own. However, the only remedy for a cracked injector is complete replacement. The electrical components of an injector can also fail from age, heat, and moisture damage, and generally require replacement of the entire unit when this is the case.

A faulty or clogged fuel injector will likely cause an engine to misfire because one or more of the cylinders is not receiving the fuel it needs to run properly. These misfires are usually felt as a rough idle or lack of power, and may go hand in hand with a check engine light. If a fuel injector is still spraying and working properly but is leaking, there will likely be a fuel smell present while the vehicle is running.

A leaking fuel injector is a definite safety concern, as the leaking fuel and vapors can ignite under the hood and cause a fast-spreading fire. An injector that is clogged or stops working is not a fire risk, but will cause the vehicle to run poorly, or not pass a smog check in California.

Additionally, it can lead to internal engine damage from fuel starvation over a longer time period. By addressing fuel injector issues when they arise, hazards and costly repair bills may be prevented.

If a fuel injector is found to be faulty, it may or may not be recommended to replace all of the injectors based on their age & condition - the mechanic working on the vehicle will be able to make the best recommendation in the case of your specific vehicle.

When replacing injectors, it is also necessary to replace the small rubber o-ring seals that seal the injector and prevent fuel vapors from escaping. If the seals are not replaced, fuel leaks may present themselves soon after the repairs are completed.

A fuel injection cleaning service may be recommended at the same time an injector is replaced if there are signs of carbon buildup. This is a valuable time to perform this service, if it is needed, because it will help ensure the fuel injection system is running as best as possible following the repairs.

An engine air filter is a paper, foam, stainless steel mesh, oil bath, water bath, or cotton media filter that traps particles from the air before they enter the combustion process of automotive engines. On modern vehicles, paper, foam, and cotton media are the most commonly seen.

The types of particles trapped by this filter are everything from dirt and dust from the air, to insects, tree leaves, and anything else that might damage the inner workings of an engine.

Air filters can be square, rectangular, round, or cylindrical in shape, depending on the vehicle application.

Because it traps particles from the air which could potentially damage internal components of the engine, the air filter is a vital part of the air intake system on modern vehicles. Its function also helps prevent the engine oil from becoming contaminated with debris from the air. Both of these heavily contribute to proper running of an engine, and longevity of its internal components.

The most common thing to happen to an engine air filter is that it becomes saturated with particles from the air, and needs to be changed. Replacement of this filter is found on every vehicle's maintenance schedule, usually between every 30,000 and 40,000 miles.

Many dusty areas, or areas with lots of pollen in the air will need to increase the frequency of the filter changes because they will become contaminated more quickly. When a filter starts collecting contaminants, it also gradually begins to restrict the air flow going to the engine. Replacement of the filter when needed, or on schedule helps make sure the engine always has the clean air it needs to use in the combustion process.

Another important part of an air filter that can sometimes fail is its sealing surface. In order to ensure that all the air going into the engine gets filtered, air filters have a rubber seal around them that seals against the air intake box. This seal needs to be airtight in order to be effective. The most common reason the seal fails is due to improper installation, but it can also degrade over time if contaminated with automotive fluids, like engine oil or grease.

If your vehicle's maintenance schedule is calling for engine air filter replacement, it should definitely be done. If your vehicle is being serviced at an interval that doesn't call for engine air filter replacement, most shops will inspect the engine air filter for you to ensure it's in good shape. In the event that the filter looks dark or black, or there is noticeable buildup of debris in the filter media, it's a good idea to have it changed.

There are many signs that you may need a radiator replacement. Some common symptoms are overheating, rust on the radiator, leakage, or failures in the cooling system or water pump.

The faulty radiator will be removed and replaced with a new radiator with proper coolant levels. Coolant hose, thermostat and temp sensors are also inspected and may require replacement.

The cooling system of your car is essential to the proper function of the vehicle. Replacing a radiator or any of its components may involve a computer relearn but can usually be done within one day.