Replacing Air-Fuel Ratio Sensor: 2010 Corolla Guide

If the check engine light comes on, your air fuel ratio sensor may have failed. This sensor, also known as an oxygen sensor, is important for ensuring your Toyota Corolla's engine performs optimally and does not pollute the environment. A faulty sensor can cause your car to leak gas and fuel into the air. You can replace the sensor yourself by parking your car on a flat, hard surface, disconnecting the battery, raising the vehicle, locating the sensor, disconnecting the harness, and unscrewing the sensor. Then, clean the harness and connect the new sensor. Finally, lower the vehicle, reconnect the battery, and test-drive the car.

Identify the malfunction indicator light

The malfunction indicator light, or MIL, is part of the onboard diagnostics system of your Toyota Corolla. It can appear in several ways, including:

• The text "Check Engine"
• A symbol of an engine
• A combination of the above

The light will illuminate in either an amber or red colour. A flashing light indicates a hazardous issue that could result in damage to the vehicle. If the light is flashing, do not drive the vehicle and schedule a service immediately.

If the light is not flashing, it is generally safe to drive your vehicle. However, you should still get your Corolla checked as soon as possible. Ignoring the warning could cause major damage to expensive engine components.

The MIL will often shut itself off if the issue is resolved. For example, if the cause was a loose gas cap, tightening it will turn the light off.

Prepare to replace the sensor

Before you start work on your 2010 Corolla, there are a number of steps you should take to prepare to replace the air fuel ratio sensor. Firstly, park your vehicle on a flat, hard surface, and make sure the transmission is in park if it's an automatic, or in first gear if it's a manual. This step is only necessary for vehicles with all-wheel-drive or rear-wheel-drive transmissions.

Next, place wheel chocks around the rear tires and engage the parking brake to prevent the vehicle from moving. Install a nine-volt battery saver into the cigarette lighter to keep your computer live and ensure your settings remain current. If you don't have a battery saver, that's fine, just move on to the next step.

Now, open the vehicle's hood and disconnect the battery. Take the ground cable off of the battery's negative post to disable the power to the air fuel ratio sensor. If you have a hybrid vehicle, refer to the owner's manual for disconnecting the small battery only.

Using a floor jack, lift the vehicle at its specified jacking points until the wheels are off the ground. Consult the vehicle's owner's manual for the correct jacking locations. Once the vehicle is raised, place jack stands under the jacking locations and lower the vehicle onto the stands.

You are now ready to begin removing the air fuel ratio sensor.

Remove the sensor

To remove the air fuel ratio sensor, follow these steps:

Park your 2010 Corolla on a flat, hard surface and ensure the transmission is in park for automatics or in first gear for manuals. Place wheel chocks around the rear tires and engage the parking brake to prevent the vehicle from moving.

Open the hood and disconnect the battery by removing the ground cable from the battery's negative post, disabling power to the sensor. If you have a hybrid Corolla, refer to the owner's manual for instructions on disconnecting the battery.

Using a floor jack, lift the vehicle at its jacking points until the wheels are off the ground. Place jack stands under the jacking locations and lower the vehicle onto them. For most cars, the jacking points will be on the pinch weld under the doors along the bottom of the car.

Get your tools and creeper, and locate the air fuel ratio sensor. Determine if you need to remove the exhaust or another component to access the sensor. If you need to remove the exhaust, locate the mounting bolts closest to the front of the sensor and remove them, along with the butt connectors to the upstream and downstream sensors.

If the exhaust pipe goes around a drive shaft, you will need to remove the drive shaft before lowering the exhaust. Remove the mounting bolts and push that section of the drive shaft into its slip yoke. If the vehicle has a center support bearing, remove it as well.

If your Corolla is equipped with an engine guard, use a fastener remover to take off the plastic fasteners holding it in place. Lower the engine guard and set it aside.

Disconnect the harness from the air fuel ratio sensor. If the sensor is stuck, you may need to use a small portable torch to heat up the area around the mounting surface. Be careful, as the exhaust pipe will be very hot.

Use a breaker bar and the air fuel ratio sensor socket to remove the sensor from the exhaust pipe.

Install the new sensor

Now that you've disconnected the harness from the old air fuel ratio sensor and removed it from the exhaust pipe, it's time to install the new one.

First, take the new sensor out of its box and clean the contacts with electrical contact cleaner to ensure no debris is present. Next, thread the sensor into the exhaust pipe. Tighten the sensor with your hands as far as you can, and then use a wrench to tighten it further to the specifications provided on the slip in the bag or box that the sensor came with. If there is no slip provided, and you don't know the specifications, you can tighten the sensor by a half turn with metric 12 threads and a three-quarter turn with metric 18 threads. If you don't know the thread size of your sensor, you can use a metric thread pitch gauge to measure it.

Once the sensor is tightened, connect the butt connector on the air fuel ratio sensor to the vehicle harness. Make sure that the lock is in place if there is one.

Check the engine

The engine is considered the "heart" of a vehicle as it produces the power required to move it. Depending on the type of powertrain, the engine can be found at the front or back of the vehicle. There are three types of engines: internal combustion engines, electric motors, and hybrid engines.

Internal combustion engines generate power by burning fuel inside the engine and converting the heat produced. They are made up of several parts, including a cylinder block, crankshaft, pistons, and valves. The cylinder block is a hollow chamber that houses the pistons and is usually made of cast iron or aluminum. The crankshaft is a long rod that transfers power from the engine to the drivetrain, and it is attached to the pistons via connecting rods. The pistons move up and down inside the cylinder block, and the valves control the flow of air and fuel into and out of the cylinder.

Electric motors, on the other hand, generate power from electric current rather than fuel. They consist of a stator, which generates the magnetic field, a rotor, which rotates and generates current, and a commutator, which changes the direction of the current to control the motor's rotation.

Hybrid engines combine an internal combustion engine and an electric motor, allowing the vehicle to switch between the two power sources depending on driving conditions.

When checking the engine of a car, it is typically located under the bonnet at the front. However, some sports cars have a mid or rear-engine configuration, with the engine placed behind the driver or the rear passenger seats, respectively.

Frequently asked questions