An oxygen sensor is constantly exposed to hot exhaust gases while monitoring the amount of oxygen in the exhaust stream. Over time, that harsh environment can wear the sensor down. In other cases, an engine problem can contaminate or overheat the sensor long before its normal service life is reached. The most common causes of…
An oxygen sensor is one of the main sensors your vehicle uses to monitor how efficiently the engine is burning fuel. It measures the amount of oxygen remaining in the exhaust and sends that information to the engine control module, or ECM/PCM. The computer then uses the signal from certain oxygen sensors to adjust the…
Common symptoms of a bad oxygen sensor include a check engine light, poor fuel economy, rough idle, hesitation, failed emissions testing, unusual exhaust smell, and fuel-mixture problems. The symptoms of a bad oxygen sensor can vary depending on which sensor has failed and whether it is located before or after the catalytic converter. A faulty…
Oxygen sensors may look similar from one vehicle to another, which can make it seem like any sensor with the right thread size should work. In reality, compatibility depends on much more than whether the sensor physically screws into the exhaust. No, oxygen sensors are not universally interchangeable. Some universal O2 sensors can work on…
An oxygen sensor is an exhaust-system sensor that measures oxygen in the exhaust gases so the engine computer can adjust the air-fuel mixture and monitor catalytic-converter performance. If you drive a modern gasoline-powered vehicle, there is a very good chance it has more than one oxygen sensor working every time the engine runs. These small…
A faulty positive crankcase ventilation (PCV) valve can affect how crankcase vapors are routed back into the engine. On vehicles that use a separate replaceable PCV valve, replacing it is often a relatively simple maintenance or repair job that requires only basic hand tools. To replace a PCV valve, locate the valve on or near…
You can sometimes clean the accessible PCV hose, port, and light deposits around the valve without removing the PCV valve, but you usually cannot thoroughly clean the valve’s internal mechanism while it remains installed. If the valve is sticking, clogged internally, or built into the valve cover, removal, replacement, or vehicle-specific service is often the…
A faulty PCV valve can cause rough idle, vacuum leaks, abnormal crankcase pressure, oil consumption, and sometimes lean-condition or misfire trouble codes. Fortunately, you do not always need to remove the valve immediately to get useful information about whether the PCV system is working correctly. You can test a PCV valve without removing it by…
The positive crankcase ventilation (PCV) valve is a small engine component, but it plays an important role in controlling crankcase pressure and routing blow-by gases back into the intake system. Because the PCV valve constantly handles oil vapor, moisture, and combustion gases, it can eventually become restricted, stuck, or worn. A traditional PCV valve often…