Should you drive with a bad oxygen sensor (O2 sensor)?
The short answer is no.
You’ll technically be able to start and drive your car with a faulty O2 sensor, but you’ll likely face poor engine performance and a drop in fuel economy.
So, what happens if you ignore the issue?
Read on to explore why driving with a faulty sensor is inadvisable, the bad oxygen sensor symptoms to watch out for, and more.
This Article Contains:
- Can You Drive with a Bad O2 Sensor?
- How Do You Know if Your Oxygen Sensor Is Bad?
- What Causes a Malfunctioning O2 Sensor?
- 3 FAQs about Oxygen Sensors
Let’s go!
Can You Drive with a Bad O2 Sensor?
A bad oxygen sensor won’t put your car out of action. However, driving with a faulty sensor can have several negative impacts, including:
1. It’ll Lead to an Improper Air-Fuel Mixture
If the upstream O2 sensor malfunctions, the Powertrain Control Module (PCM) will get inaccurate exhaust oxygen level readings and cannot adjust fuel delivery properly. This could lead to either too much fuel (rich mixture) or too little fuel (lean mixture) in the combustion chamber.
When this happens, you may experience an engine misfire and engine damage (if the issue is unaddressed).
2. You’ll Experience Rough Running and Sluggish Acceleration
An improper air-fuel mixture can cause incomplete combustion, which impacts how smoothly your car runs.
It typically manifests as rough idling, rough running, and sluggish acceleration. However, it can also lead to stalling — a safety risk on the road.
3. Your Fuel Consumption Will Increase
A faulty oxygen sensor can indicate an incorrect air ratio in the combustion chamber than what’s present.
If it indicates a low air ratio, the PCM would send excess fuel to the combustion chamber, increasing fuel consumption.
If it indicates a high air ratio, the engine will run lean since the PCM would send less fuel. This could reduce gas mileage since a lean mixture can cause incomplete combustion, and the engine will need more fuel to compensate for the decreased power.
4. The Catalytic Converter Will Clog
When your engine runs rich due to a faulty O2 sensor, the unburnt excess fuel will be let into the exhaust, where it clogs the catalytic converter.
It could also overheat and damage the catalytic converter. If that happens, you’ll need a catalytic converter replacement, which is more than double the cost of a bad sensor replacement.
Plus, a bad catalytic converter will lead to increased emissions and failed pollution tests.
But before you jump to a replacement, let’s confirm if you have a faulty oxygen sensor by reviewing bad o2 sensor symptoms.
How Do You Know if Your Oxygen Sensor Is Bad?
Check for these bad O2 sensor symptoms.
- Lit check engine light (CEL): A faulty O2 sensor is one of the most common reasons behind an illuminated CEL. This lit warning light may be because the bad sensor (upstream sensor) relays inaccurate readings to the Powertrain Control Module or shows a low oxygen level.
- Poor fuel efficiency: As mentioned above, a broken oxygen sensor will reduce fuel economy since it causes an imbalance in the air-fuel mixture.
- Reduced engine performance: You’ll notice poor engine performance, like rough running, sluggish acceleration, rough idling, engine misfire, and stalling. You may also hear knocking or pinging noises.
- Rotten smell: Another prominent sign of a broken oxygen sensor (downstream O2 sensor) is a rotten smell from exhaust gas. The smell is due to a failing catalytic converter that’s unable to convert hydrogen sulfide into less harmful emissions (odorless sulfur dioxide). You may also see increased emissions or black smoke from the tailpipe.
Note: A lit check engine light and poor fuel efficiency may occur for several other reasons, including malfunctioning spark plugs and fuel injectors. It’s best to have a professional mechanic confirm the underlying cause of your issues before getting a replacement.
Next, let’s explore the causes behind a failing oxygen sensor.
What Causes a Malfunctioning O2 Sensor?
A failing oxygen sensor may be due to:
- General wear: Oxygen sensors, like any other components, can wear out over time and use. So, if your car is old, it’s best to have your sensors checked and maintained as recommended in your owner’s manual.
- Low-quality fuel: Old and poor-quality fuel contains more contaminants that can damage an oxygen sensor. That’s why you need to stick to high-quality fuel that meets the octane requirements specified in your owner’s manual.
- Electrical issues: Corroded wiring, damaged connectors, and short circuits can disrupt your O2 sensor’s communication with the PCM. Although this isn’t direct O2 sensor failure, it does lead to a malfunction that can trigger the check engine light.
- Ignoring regular maintenance: Missing scheduled maintenance, which includes air filter or spark plug replacements, can lead to grime build-up in the emissions system. It can lead to hastened wear and O2 sensor failure.
Still have doubts?
Let’s explore more about O2 sensors.
3 FAQs about Oxygen Sensors
Here are answers to queries you may have about O2 sensors:
1. How Does a Car O2 Sensor Work?
Your car has two types of oxygen sensors on each exhaust pipe:
- An upstream O2 sensor that measures the exhaust gas oxygen content.
- A downstream O2 sensor to monitor the catalytic converter’s output and health.
These sensors track the amount of oxygen entering the exhaust and exiting the catalytic converter and relay the information to the PCM.
So, the upstream sensor helps adjust fuel delivery to ensure optimal fuel usage and engine performance. And the downstream sensor helps ensure the vehicle maintains proper emission levels.
2. How Often Do You Need to Replace an O2 Sensor?
An oxygen sensor typically lasts between 30,000 to 100,000 miles.
However, you should have the sensors checked when your vehicle has over 60,000 miles or if the part is more than 15 years old. If a sensor shows signs of failure, it’s best to replace it.
3. How Much Does it Cost to Replace a Bad O2 Sensor?
An O2 sensor is important for your vehicle’s performance and safety. So, it’s best to have any replacements done by a professional.
Here are estimates for oxygen sensor and catalytic converter replacements (with labor charges):
- O2 sensor: $200 to $500
- Catalytic converter: $450 to $2600
Note: You can also purchase a cleaner to unclog your catalytic converter for about $8 to $20.
Fix Your Bad O2 Sensor with AutoNation Mobile Service
A malfunctioning O2 sensor can lead to bad gas mileage and engine performance, not to mention fines if you fail the emissions test. That’s why you shouldn’t drive with a bad O2 sensor.
Instead, why not let AutoNation Mobile Service come to you?
We’re a mobile auto repair and maintenance service that offers convenient bookings, upfront pricing, and a 12-month, 12,000-mile warranty.
Get in touch with us to fix a bad O2 sensor or other auto issues right from your driveway.