When Car Sensors go Bad- Symptoms for 5 Common Sensors

Car sensors are essential car parts that act as your Peugeot engine's eyes and ears. These sensors transmit information to the engine control computer and monitor all of the key function essential for fuel delivery, ignition timing, transmission shifting, engine torque reduction, alternator output changes, and emission controls. They may even be responsible for managing cruise control and throttle control.

There are a number of sensors located beneath the bonnet of your car, and their operation is critical to the function of your Peugeot. When they begin to fail, a number of problems can occur that can make it hard or even impossible to operate your vehicle. Here are just a few of the most common sensors and the symptoms that can occur when they begin to fail.

 

Car Sensors and Failure Symptoms

The Knock Sensor

What it is:

The knock sensor is typically found on the intake manifold, cylinder head, or engine block. It is responsible for sensing any vibrations in the engine and reporting this information to the engine computer system. The computer system is then able to change the ignition timing and keep detonation from occurring so the engine isn't damaged by pre-ignition.

 

Signs of Failure:

You will most often notice the symptoms of a bad knock sensor when you're driving under load or when cruising at higher speeds on the motorway. Some of the signs you might notice include:

• Loss of fuel mileage

 

• Loss of acceleration

 

• Check engine light

 

• Loud thumping noises coming from the engine caused by air and fuel igniting in the cylinder

 

• Shaking or vibrating of the car when starting the engine

You might also feel as if something doesn't 'feel right' with your car.

 

Oxygen Sensor

What it is:

Since 1981, cars have used oxygen sensors to monitor and control the mixture of air and fuel in the engine. This sensor is most often mounted on the exhaust manifold. It is responsible for measuring the amount of oxygen remaining in the exhaust. In cars that have V8 or V6 cylinders, one O2 sensor a piece may be placed on these Peugeot parts. The sensor will report the information it finds to the engine computer, which will adjust and rebalance the fuel mixture accordingly to provide the lowest emissions.

 

Signs of Failure:

Some of the most common signs of a failing or failed O2 sensor include:

• Poor fuel mileage

 

• Irregular or rough handling when the engine is idling

 

• Engine misfiring, which is generally more pronounced when the engine is idle

 

• Check engine light

In order to keep your emission low and fuel mileage up, you'll need to have the O2 sensor replaced as soon as possible.

 

Coolant Sensor

What it is:

The coolant sensor is typically located on one of two car parts: the intake manifold or the cylinder head. It is responsible for making sure the engine coolant stays at the right temperature. When the coolant temperature rises, it informs the engine computer so the computer can move onto other functions that require temperature control.

Signs of Failure:

While the coolant sensor is a reliable Peugeot part, it can fail on occasion. When it does, it can prevent the engine from focusing on other areas that are temperature dependent. This can result in symptoms like:

• Rich fuel mixtures

 

• Rising CO emissions

 

• Excessive fuel consumption

While you may notice you are using more petrol than usual, the first two symptoms will likely be caught when you go in for your MOT.

 

MAP Sensor

What it is:

The manifold absolute pressure, or MAP, sensor is connected to or mounted onto your Peugeot's intake manifold. It is responsible for monitoring the intake vacuum and will change the frequency or voltage when the pressure in the manifold changes. This information is sent to the engine computer regularly so ignition timing can be altered as needed.

On certain cars with speed density fuel injections, this sensor is also responsible for helping the computer estimate the amount of airflow necessary.

Signs of Failure:

Cars with bad map sensors will still function, but they won't function well. The computer can estimate the data itself, but it won't be as accurate and engine function will be reduced. When this happens, you'll likely experience symptoms like:

• A slight jerking or moment of hesitation when you accelerate

 

• High fuel consumption

 

• The car might stall when you push down on the accelerator to begin movement

 

• Rough idling

 

• An inappropriate fuel mixture, which can be accompanies by knocking sounds in the engine or the smell of petrol

A mechanic can diagnose this sensor problem. The sensor should be replaced as quickly as possible to eliminate the symptoms.

 

MAF Sensor

What it is:

The MAF, or mass airflow, sensor is typically located just ahead of the throttle body on some fuel-injected engines. It is responsible for measuring the amount of air that comes into the engine and reporting that amount to the engine computer. A heated filament or hot wire is typically used by the sensor to measure the flow and density.

Signs of Failure:

Unfortunately, the hot wire or heated filament used by this sensor can become contaminated easily by dirt, dust, and road debris. This can result in:

• Rough idling

 

• Stalling problems

 

• Hesitation upon acceleration

 

• Hard starting

 

Fortunately, these sensors don't always need to be replaced if they begin to fail. Sometimes they can simply be cleaned and restored to their normal function.

The sensors in your car work with your engine's computer to ensure every part of the engine is functioning properly. These sensors are essential Peugeot parts and should be taken very seriously. If you suspect that one of your sensors is failing, consult a professional mechanic as soon as possible. They will be able to perform a diagnostic check and determine which sensor is going bad. Once it is cleaned or replaced, your car will be able to return to its normal function.