If you’ve ever experienced your car suddenly shutting off while driving, it’s a terrifying experience! If you’re just here to know if a bad O2 sensor can cause a car to shut off? The answer is it’s very unlikely, the vehicle can stall or misfire with a bad O2 sensor, but to cause a car to shut off while driving, the problem will usually be something else. To point out, though, a bad oxygen sensor may have caused the other problem! If you want to know more about what’s happening, keep reading.
What is an O2 sensor and how do they work?
A car O2 sensor, also known as an oxygen sensor or Lambda sensor, is a device located in the exhaust system usually either side of the catalytic converter that measures the amount of oxygen in the exhaust gases. The sensor sends this information to the vehicle’s engine control unit (ECU), and adjusts the air-to-fuel ratio mixed for combustion. This helps to ensure that the engine is running efficiently and producing as little pollution as possible.
The O2 sensor before the catalytic converter measures the amount of oxygen in the exhaust gases as they leave the engine and before they enter the catalytic converter. The O2 sensor after the catalytic converter measures the amount of oxygen in the exhaust gases after they have been through a chemical reaction inside the catalytic converter.
What causes an O2 sensor to go bad?
- Age – O2 sensors have a limited lifespan, because of the environment and the fact they are under the car open to the elements, the sensor can corrode. Over time, the sensor can become less accurate and less responsive.
- Contamination – Dirt, oil, unburnt fuel, coolant, and other contaminants (including a leaking exhaust) can build up on the sensor inside the exhaust and interfere with its ability to measure oxygen levels accurately. Although this does indicate, there is possibly something else causing a problem within the engine, causing the sensor to fail.
- High temperatures – O2 sensors operate at high temperatures, but exposure to increased temperatures from problems such as a clogged catalytic converter can reduce the life of the sensor.
- Physical damage – The sensor can be damaged by an impact, which can obviously cause it to fail. The other physical damage that is quite common is when an old sensor is removed from the exhaust to change the catalytic converter and the thread strips as its removed, meaning it can no longer be reused.
- Electrical problems – Split wiring will cause the sensor to fail completely until the wiring is reconnected. But, a dodgy crimp in the connector block can cause the connector to get very hot melt the plastic surround and the wiring will be burnt out.
Symptoms of a failing O2 Sensor
The most obvious and common symptom of a failing O2 sensor is the engine management light illuminated on the dashboard. As the O2 sensor is an electrical sensor, any defect with its operation that is out of sync with the car is programmed to perform, and the light will come on. The slight problem is that without actually plugging the vehicle into a code reader, it’s impossible to confirm that it’s the O2 sensor causing the fault.
There are other symptoms of a failing O2 sensor when the light doesn’t come on yet because the sensor isn’t quite so bad, which aren’t so noticeable. They include:
- Slight increase in fuel consumption
- Excess exhaust smoke
- Increase emissions (detected at an emissions test)
- Rough running engine
- Minor misfire (detected as a slight vibration through the car)
These are all straightforward problems that are simple to pinpoint to the oxygen sensor using a diagnostic tool and live data. Unfortunately, without a diagnostic tool, you would be guessing that the O2 sensor is starting to fail.
Will a bad O2 sensor cause car to shut off?
A bad O2 sensor alone is unlikely to cause a car to shut off completely while driving. However, if the O2 sensor is malfunctioning or fails, it can cause various issues affecting the engine’s performance. For example, a faulty O2 sensor can cause the engine to run too rich or too lean, which can cause the engine to misfire or stall. In some cases, a malfunctioning O2 sensor can also cause the engine to run rough, have reduced power, and hesitate on acceleration.
Is it safe to drive with a bad O2 sensor?
Driving with a bad O2 sensor is not about whether the car is safe. The problem with driving is how much damage is being done to the engine and catalytic converter.. With the air/fuel mixture being incorrect the chances of another component failing is very high. The other problem is that without plugging the car into a diagnostic machine, how can you be sure the problem is not even more severe than an oxygen sensor failing?
Other factors that can cause a car to shut off
The amount of other components on a car that can cause it to shut off is enormous; this list could go on for days. The most common problems are:
- Bad crankshaft position sensor
- Fuel supply problems
- Bad alternator
- Ignition lock
- Empty fuel tank
- Faulty fuel pump
- Dirty fuel filter
- No fuel injection
- Faulty throttle body
- Clogged air filter
- Faulty MAF sensor
- Faulty MAP sensor
- Faulty engine control unit
- Catalytic converter problems
- Faulty ignition switch
- Dead battery
Although an O2 sensor is unlikely to cause the car to shut off while driving, it can cause many other noticeable problems. The other big problem with a failed or failing oxygen sensor is that it can damage other components of the car, and when they fail, it can cause an enormous repair bill for something as simple as a little exhaust sensor.
We recommend reading this next similar article: Can a bad catalytic converter cause the car to shut off? Explained!