Is your “Check Engine” light on?
If it is, don’t panic just yet. The warning is an early indication of a malfunction. While the problem is usually minor, it must nevertheless be checked and rectified – ASAP.
The “Check Engine” light is illuminated when the car’s ECU (engine control unit) detects an abnormality in one of several engine performance or emissions functions.
WHAT IS A VACUUM LEAK?
Your car is not a vacuum cleaner, so how can it have a vacuum leak?
In automotive terms, a vacuum leak means that a certain amount of air has bypassed the usual engine intake tract.
Under normal conditions, all of the engine’s intake air is routed through the throttle body. Inside the throttle body is where the mass air-flow sensor accurately measures the quantity of air going into the engine.
When a vacuum leak occurs, some air enters the intake manifold without passing through the throttle body. The ECU, meanwhile, injects the amount of fuel necessary based only on the measured air-flow.
This results in a lean fuel-air mixture, which then leads to erratic idling and lacklustre low-speed performance.
O2 (OXYGEN) SENSOR
What part does the oxygen sensor play in the case of a vacuum leak?
Recall that the oxygen sensor is a component of the engine management system that measures residual oxygen in the exhaust gases.
Because of the excess air intake, this data will not tally with ECU-measured air-flow, which then leads to the “Check Engine” light being triggered.
WHAT CAUSES A VACUUM LEAK?
The probable cause of a vacuum leak is a cracked intake hose or a break in one of the several rubber tubes connected to the intake manifold. These parts deteriorate over time and become brittle.
The fault is not difficult to find. It is relatively easy and inexpensive to rectify, too.
Although a leak is unlikely to cause major problems, you should have it fixed so the engine can perform optimally.