The compression check must be performed using a special compressor. First we need to warm the engine to the operating temperature. Then we need to turn off the low-voltage cables from the ignition module. After this, candles are lit up (in the 16-valve Renault Sandero C4M engine). Then we disconnect the fuel pump by removing the relay from the mounting block. On the gas pedal, we turn the compressor on the gas pedal, and we turn on the starter for a few seconds. In the same way we measure compression in other cylinders. It shall have a value of at least 10 bar (1 MPa) and must not differ in different cylinders by more than 1 bar.
