Oxygen Sensor

Automotive oxygen sensors, also known as lambda sensor or O2 sensors are used in most cars both in the US and in other countries. It is an electronic device which measures the proportion of oxygen (O2) in the gas of an automobile. It was developed by the Robert Bosch GmbH company during the late 1960s under the supervision of Dr. Gunter Bauman. It also makes modern electronic fuel injection and emission control possible. It helps determine if the air fuel ratio of a combustion engine is rich or lean. The sensor does not actually measure oxygen concentration; instead, it measures the amount of oxygen needed to completely oxidize and remaining combustibles in the exhaust gas.

Oxygen sensors, along with catalytic converters are used by modern spark-ignited combustion engines to reduce exhaust emissions. Information on oxygen concentration is sent to the engine management computer, which adjusts the amount of fuel injected into the engine to compensate for excess air or excess fuel. Tampering with or modifying the signal that the oxygen sensor sends to the engine computer can be detrimental to emission control and can even damage the vehicle. Failure of sensors, either through normal aging, the use of leaded fuels, or fuel contaminated with silicones or silicates, can lead to damage of an automobile’s catalytic converter and extensive repairs.

By 1996, all cars have multiple 02 sensors. One is located in between the engine and catalytic converter, while the other is positioned behind the catalytic converter. The engine control module monitors the extra sensor to verify the efficiency of the catalytic converter. With normal operation, this oxygen sensor produces almost no voltage because the catalytic converter consumes everything.

The normal lifetime of an unheated sensor is 30,000 to 50,000 miles (50,000 to 80,000 km), while the lifetime of a heated sensor is typically 100,000 miles (16,000 km). The symptoms of a failing oxygen sensor include:

  • Sensor light on dash indicates problem
  • Increased tailpipe emissions
  • Increased fuel consumption
  • Hesitation on acceleration
  • Stalling
  • Rough idling

When the oxygen sensor fails, the computer can no longer sense the air/fuel ratio, so it ends up guessing. The car performs poorly and uses more fuel than it needs to.


Driving Tactics to Save Gas

It appears that fuel prices will continue to rise. In a month, more fuel hikes are experienced by motorists over rollbacks. To help with the problem of rising fuel costs, here are some driving tactics for the burdened motorists.

1. Coast to a Stop
It is common knowledge that accelerating up to the last moment then braking hard to stop is totally wasteful. It lowers the fuel economy rating of the car. Hence, coasting to a stop is the better way to go. Easing of the gas at a considerable distance from a stop sign and allowing the vehicle to cruise using the remaining kinetic energy can increase a car’s fuel economy.

2. Avoid Slowly Crawling Up to Speed
Apparently, nursing your speed up to the limit too slowly increases fuel consumption. The recommended acceleration rate for maximum fuel efficiency is 50 mph in 15 seconds.

3. Close Windows and Use A/C at High Speeds
Open or close windows? This has been a long standing debate. Running the A/C with the windows closed preserves the car’s aerodynamic profile causing less drag and more fuel saved. Others argue that running with open windows saves more fuel since A/C is not being used. An experiment was performed and a concrete answer was given to end this debate. Below 55 mph, open the windows and leave the a/c off. But at 60 mph or higher, keeping them closed and the air conditioning running will burn less fuel.

4. Cruise at a Slower Speed
Some studies suggest that the 55 mph speed limit saves the most fuel while going beyond 80 decreases mpg. So, it is best to stay between 55 to 80 mph.

5. Climb Slowly
The ascent uses more fuel than the descent. So if it’s safe, ascend slowly and cautiously. Lifting off the accelerator while traveling up the hill and allowing your speed to decay trades some kinetic energy for potential energy. You regain the kinetic energy—and get better gas mileage—on the backside.

6. When Coasting Downhill, Leave the Car in Gear
Experiments show that popping the car to neutral actually wastes gas. So put your car in gear when going downhill.

Aside from the six driving tactics mentioned, here are some basic fuel saving techniques every driver should remember:

1. Monitor Tire Pressure
Low tire pressure increases rolling resistance. So keep your tires properly inflated.

2. Warm Up the Engine
Cars are more fuel efficient when the engine is warm. A fully-warmed up engine will still work efficiently even after it’s parked for 30 minutes.

3. Plan errands carefully
Reduce fuel consumption by doing all errands in one go. Start with the farthest and end with the closest destination.

Hopefully these tips can lessen the burden on motorists brought about by the continuous rise in fuel prices. And let’s all hope for more fuel rollbacks in the near future.