Modern cars contain a wealth of sensors. Depending on the year of manufacture and the model, the typical car will contain between 60 to 100 sensors, and some even think that number could expand to 200, as cars get smarter and smarter.
These sensors perform a range of functions, monitoring many systems and providing feedback and operational data whilst the car is operating. They will also highlight problems, often before you even notice any other symptoms.
Half the time, when you take a modern car to a mechanic they are plugging it onto a laptop and the car is telling them exactly what’s wrong (unless your car is a little older of course, in which case it might be a case of getting a bit dirty and having a dig around it’s insides).
Even with all these sensors though, things can still go wrong with your car without triggering any warning lights. These can often be easy to spot – you don’t need a warning light to tell you that your rear tire has blown for example!
But sometimes the problems can be harder to pin down. Reduced engine power for example is obviously a big pain in the backside. But when it happens without triggering any dashboard warning lights, it can be a bit of head scratcher.
Luckily, if your engine is losing power without triggering warning lights, that suggests it’s probably 1 of 4 potential issues. What’s more, all of these issues can be tackled at home saving expensive trips to the mechanic.
Step this way then to discover the big 4 and how to repair them to get your engine purring along again at full power.
1. Dirty Air Flow Sensor
What is it?
After all that talk of sensors and how they can help your car, it only seems fitting to start with how failed sensor can actually harm it!
This little gadget, as it’s name implies, is responsible for monitoring the air that is drawn into your car’s engine. This air is a vital part of the combustion process that is at the heart of your engine, so monitoring the air intake is of course equally vital.
The airflow sensor in your car works by allowing air to pass over a heated wire. As the airflow increases or decreases so it affects the temperature of the heated wire. Depending on this measurement, the engine increases or decreases the amount of gasoline that is used in the combustion process.
The trouble occurs when the wire starts to get dirty – in this instance, it can start to give false readings. These false readings then cause the engine to inject less gasoline than it should into the combustion process, leading to – you guessed it – a reduction in engine power.
How to fix it
There are a couple of ways to tell if your air sensor is not working correctly. First, start the engine then pop the hood. Locate the sensor and give it a couple of sharp taps – if the engine falters slightly, you have a dirty sensor.
Alternatively, disconnect the sensor then start the engine. The engine will recognize it has been removed and will go into a back-up running mode. If it runs better without the sensor working, again this shows it has been damaged or is dirty.
Thankfully, this is a pretty simple fault with a pretty simple fix. The best way to clean it with an Air Sensor cleaner that you can buy online or in good auto shops. Remove the sensor and spray a few bursts of the cleaner as per the instructions on the can.
Replace the sensor and enjoy a return to your usual engine power!
2. Dirty Air Filters
What is it?
An air filter, as the name implies, filters the air that is entering your engine. It does this to keep dirt and other containments out of the main engine, helping to keep it clean and running efficiently.
That being said, over time the air filters will experience build up of all the stuff that they are filtering out of the airflow. When this build up gets too much, the filter will start to restrict airflow – and as we discussed above air is a vital part of the running of your engine.
The air filter itself is not connected to any sensors that monitor this accumulation of dirt, so there is no warning light to show that the air filter is not working properly. Instead, you’ll simple notice an overall reduction in engine power.
How to fix it
The first step is to inspect the air filter, but before you can do that you need to find it!
In almost all modern cars, the air filter is located in a rectangular plastic box usually tucked to one side of the engine block near the inside of a fender. The rectangular box is a called a “Cold Air Collector Box,” if you are referring to your vehicle manual.
Older vehicles will tend to have the air filter sitting right atop the engine block. This time, it will be a large, round item with an opening for air intake set to one side.
In both cases, you need to open the container the air filter is in – whether it is the rectangular or circle style box.
Remove the filter itself and hold it up to the light. If no or very little light comes through, your air filter is clogged! Tap it – gently – against a hard surface and watch all the dirt and grime tumble off.
If you hold it up again and can see the light then it’s either clean enough to use, or you’ve died. If you’re still alive, replace the filter and you’re all ready to go. If it’s still clogged, then it’s time to buy a replacement.
3. An Underperforming Fuel Pump
What is it?
A fuel pump is an integral part of the fuel system in a modern car. Sometimes they are actually powered by the engine itself, but usual they are electrically driven and located in the fuel tank.
The pump will naturally age over time and begin to lose effectiveness. There are also some things you can do whilst driving that can have a negative impact on the fuel pump. For example, the fuel in the tank is also used as a coolant to moderate the pump’s temperature when it is running. If you frequently drive your car when it is low on fuel, the pump will not be cooled effectively, and this will shorten its lifespan.
So make sure you top up the tank frequently!
Again, no sensor is attached to the fuel pump so the only indication of its performance – or lack off – is when the engine starts to feel underpowered.
How to fix it:
Oddly, the first thing to do if you suspect a fuel pump issue is – strangely enough – to not check or replace the fuel pump.
Bear with us here, we haven’t gone mad.
The truth is, checking and replacing the fuel pump is the most complicated job in this article. It is still achievable for any good at home mechanic (such as we assume you are, of course) but it is more involved than simply removing a filter and banging it.
The first thing to do is to actually check the fuel filter. This is a far more straightforward procedure, and it is more likely to be the issue if your fuel supply is restricting engine performance.
If that doesn’t solve the problem, there are a couple of methods to check and replace your pump.
4. Worn Out Catalytic Converter
What is it?
All cars built since 1975 are fitted with catalytic converters. These devices are integral to the exhaust system. All exhaust gases produced by the engine pass through the catalytic converter before they exit through the tail pipe.
The converter effectively scrubs the most harmful compounds from the exhaust. For example, it changes highly poisonous Carbon Monoxide into much safer Carbon Dioxide.
All cars must have a converter, it is illegal to operate a car without one installed. We mention this because many people will point to the converter as a major cause of engine power loss – even when they are working effectively.
It is actually a myth that they cause major loss in performance. That do affect engine performance because they restrict the flow of exhaust gases – but when they work properly, they only cause a reduction in power of between 1% to 3%.
How to fix it?
They will however start to seriously impact performance as they age. The converter is long, rectangular box that is attached to the exhaust system under your car. Inside, it is probably filled with a metal honeycomb like structure (in older models, it could be full of ceramic beads).
The honeycomb (or beads) will slow the passage of gases and over time they will clog with containments, crack and generally break down. When this happens, exhaust from the engine cannot pass through freely, which will have a negative impact on engine performance.
It is not possible to repair a failed converter. Instead, it must be replaced with a brand new model. They can be expensive because they contain precious metals (which are the catalysts that change the dangerous compounds to safer ones).
If you can replace it yourself however, you will of course avoid expensive mechanic bills and keep the overall cost down.