Switches and Sensors
Fits CITROËN C4 PICASSO I MPV (UD_) 2.0 HDi 138
(2006)

What are car switches and sensors?

Sensors for cars are devices that detect changes or variations in the environment or function of a vehicle and transmit this information to the car's computer system. Switches and sensors play a critical role in maintaining vehicle performance, improving fuel efficiency, and ensuring safe driving conditions.

There are many different types of sensors used in modern cars, each with its own unique function.

Some of the most common sensors are:

• Oxygen sensors (Lambda Sensors): Monitor the levels of oxygen in the exhaust system to optimise fuel efficiency and reduce emissions

• Mass airflow sensors: Measure the amount of air entering the engine and adjust fuel delivery accordingly

• Air temperature sensors: Provides the engine control unit with an important measurement for correcting the mixture formation and the ignition

• Fuel pressure sensors: This sensor sends this signal to the engine control unit, which then uses it to adjust the vehicle's fuel and timing settings

• Oil pressure sensors: In the event of a low or no oil situation this sensor gives you enough warning to shut your engine off before any damage is caused

How do I choose the correct switches and sensors?

There are different compatibility factors to consider when finding the correct switch or sensor for your vehicle. The surest way to obtain the correct part is to cross reference the part number from the part that you need to replace.

It is not alway possible or convenient to obtain the part number from the old part so we would advise looking out for the following factors:

• The year the vehicle was manufactured. This is not to be confused with the registration date

• List of features the switch is listed for

• Location of the sensor (i.e. after catalytic converter or before turbo etc)

• Colour or shape of the connector

• Number of wires in the connector

What brand of switch or sensor should I choose?

There are many aftermarket makers of switches and sensors and it can be difficult to know which brand you should buy. Very often the choice of which manufacture to choose is a budget led decision. All of the switches and sensors we stock come with a 1 to 3 year warranty depending on the brand. A part with a longer warranty can offer more peace of mind.

How can I tell my switch or sensor needs replacing?

We would always recommend that you have a qualified mechanic diagnose any issues you have with your vehicle. Some of the symptoms of a faulty switch or sensor are:

• The switch does not activate the required device

• There is a sensor error detected by a OBDII scanner

• Your vehicle is showing the engine management light or some other error notice on the dashboard

• The engine is not running correctly (misfire or poor performance)