This is critical for maintaining low emissions and good fuel economy. O2 sensors that are failing tend to read lean, which causes the fuel system to run overly rich to compensate. The result is increased emissions and fuel consumption. If an O2 sensor is sluggish or unresponsive, it needs to be replaced.
The same goes for any O2 sensor that has a bad internal heater circuit. O2 sensor failures can be caused by various contaminants that enter the exhaust.
These include silicates from internal engine coolant leaks due to a leaky head gasket or a crack in a cylinder wall or combustion chamber and phosphorus from excessive oil consumption due to worn rings or valve guides. Replacing a fouled O2 sensor may temporarily solve the problem, but sooner or later the new sensor also will fail if the underlying problem that is allowing the contamination to occur is not corrected.
Identifying which O2 sensor has to be replaced also can be confusing. On most and newer V6 and V8 engines, there are at least two upstream O2 sensors, and one or two downstream O2 sensors. Some engines may have as many as six O2 sensors. A fault code for an O2 sensor will indicate the sensor location by sensor number 1, 2, 3 or 4 and by cylinder bank 1 or 2. Sensor No. Bank 2 would be the other side.
Replacement O2 sensors have to be the same type as the original with the same number of wires. If one O2 sensor on a high-mileage vehicle has failed, chances are the other O2 sensors may also be nearing the end of their service life and should be replaced at the same time to restore like-new performance.
The coolant sensor keeps the PCM informed about the temperature of the coolant inside the engine. This is vital information for the PCM because many control functions vary with temperature. A faulty coolant sensor, therefore, may cause the engine to run richer than normal, resulting in increased fuel consumption and higher emissions. Coolant sensors can be damaged by overheating, so if the engine has experienced an episode of severe overeating for any reason, replacing the coolant sensor is often recommended.
It should match the air inlet temperature IAT reading when the engine is cold, and gradually increase as the engine warms up. If the sensor is not reading correctly, it needs to be replaced. The throttle position sensor TPS is mounted on the throttle body and monitors the position of the throttle opening. The TPS value is displayed on a scan tool as percentage of throttle opening.
But darned if it didn't test the heater circuit! Knock on wood, k or more on all my O2 sensors, nary a problem. Please register to post and access all features of our very popular forum. It is free and quick. Additional giveaways are planned.
Detailed information about all U. Posting Quick Reply - Please Wait. Search this Thread Advanced Search. Similar Threads Do I need to replace my Oxygen Sensor , Automotive, 18 replies How easy is it for the average car repair person to install new sensors?
How often do you replace the Oxygen sensors on your car? User Name. Remember Me. Advanced Search. View detailed profile Advanced or search site with. Search Forums Advanced. Voters: Advertisement The controller uses mV as a midpoint in a voltage range to control fuel trim for the injector pulse cycle. The voltage generated by the sensor must be greater or less than the voltage of the damping zone to send a rich or lean signal to the controller.
The damping zone acts like a shock absorber on a suspension to prevent the voltage signal from oscillating. A Planar Air Fuel Sensor is a combination of a standard Zirconium Oxide Oxygen sensor and a Pump Cell to maintain a constant sensing of a stoichiometric air fuel ratio through the extreme rich and lean conditions. The pump cell is a diffusion gap in the Zirconium Oxide of the sensor that is connected to a control circuit.
The pump cell controls the oxygen concentration of the sensor by adding or subtracting oxygen to the diffusion gap. Input to the electronic circuit modifies the oxygen concentration by changing the polarity of the current flow in the pump cell. The changing polarity of the input and trim current flow causes the control circuit to send a rich or lean signal to the engine control module.
Advertisement How long should an oxygen sensor last? An oxygen sensor should outlast the vehicle emissions warranty. Manufacturers recommend that the unheated type used from the late s to the s be inspected every 30, miles and the heated type used from the early s to the mid s be inspected every 60, miles.
Manufacturers for current generation of sensors starting in the mid s should be inspected every ,00 miles.
In fact, with proper powertrain maintenance, it is possible for the sensor to last the life of the vehicle, which could be in excess of , miles.
When does an oxygen sensor need to be replaced? The service engine soon light will come on and a diagnostic trouble code s will be stored. If the sensor is damaged or not responding, it should be replaced. Advertisement There may be multiple codes stored for a sensor. A fuel delivery malfunction can be the reason for an oxygen sensor to fail.
A fuel injector malfunction could be the root cause for the sensor failure. Just replacing the sensor may not be a long-term solution. Do oxygen sensors degrade over a period of time? Simple answer: Yes. What causes an oxygen sensor to degrade? When silicon was an ingredient in RTV and coolant, the silicon could cause the sensor to rapidly degrade. It was referred to as silicon poisoning.
So there might be two, four, or six O2 sensors in your vehicle. Yes, you can drive with a bad oxygen sensor if you can still start your engine and feel little difficulty driving.
A bad oxygen sensor could cause sluggish and rough driving with stalls, along with poor fuel efficiency and high pollution. And if you leave it there for several months, it may lead to serious problems in the engine and catalytic converter which cost thousands of dollars to fix or replace.
Thus, you need to get the oxygen sensor checked as soon as possible, like go to a mechanic during the weekend. If you have a car diagnostic tool yourself, you can read the OBD2 code and search for possible causes online and try several simple fixes. Sometimes a trouble code indicating that the O2 sensor is malfunctioning could be cleared by cleaning the O2 sensor or replacing a pipe connected. This is the simplest sign. Those warning indicators on your dash are not just pretty pictures, but they tell you when something is wrong with your vehicle.
Are you filling up your gasoline tank more often than usual? Poor oxygen sensors are one of the most common reasons for failure during an emissions test. Make sure to have your sensors checked by a mechanic prior to your first test to save you time and money.
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