Ignition Coil

This coil transforms the battery’s low voltage to the volts needed to create an electric spark in the spark plugs and ignite the fuel

>Sign of Fault: Misfires, stalling or failure to start

Air Mass Meters/Air Flow Sensors

The sensor determines how much air is coming into the engine, helping it to decide the level of fuel needed

>Sign of Fault: Rough idle

Air Temperature Sensors

This sensor monitors the temperature of air flowing into the engine. The sensor can also be used to monitor air temperature as part of the vehicle cabin.

>Sign of Fault: Increased cranking time when the engine is cold or poor fuel economy

Coolant Temperature Sensors

This sensor ensures that the engine does not overheat by measuring the temperature of the engine coolant

>Sign of Fault:  Decrease in fuel economy, engine backfires/cuts out and temperature gauge may be incorrect

Crankshaft/Camshaft Sensors

Camshaft Sensors monitors the positions of the camshaft to ensure correct ignition timing.  Crankshaft Sensor detects the position of the crankshaft and allows the ECU to calculate its position in relation to the pistons in the engine

>Sign of Fault: A faulty sensor results in loss of engine power or misfires

Exhaust Gas Recirculation (EGR) Valve

This valve helps the engine to be more efficient by recirculating a portion of the exhaust gas and running it through the combustion process again. Resulting in a cooler, more complete burn of the fuel which decreases harmful emissions.

>Sign of Fault: Loss of engine power, stuttering, jumping, black smoke from the exhaust or the car falling into ‘limp' mode

Idle Air Control Valve

This valve bypasses air around the throttle valve, controlling the speed of the engine when idle

>Sign of Fault: Erratic idling, misfiring or stalling

Knock Sensor

This sensor is mounted on the engine block and acts like a microphone, transforming vibrations caused by the sound waves from knocking into a voltage signal that can be read by the ECU

>Sign of Fault: Poor acceleration and reduced fuel economy

Manifold Absolute Pressure (MAP) Sensor

Determines the correct air/fuel ratio in vehicles which do not have an Air Mass Meter.

>Sign of Fault: Irregular engine RPM

Throttle Potentiometer

Monitors the position of the throttle valve and therefore how much air is being drawn into the engine. Allowing correct operation of the Idle Air Control Valve when the accelerator is not being pressed

>Sign of Fault: Poor idling, Misfires or Stalling