1. Oxygen Sensor: A faulty oxygen sensor can cause the check engine light to come on. The oxygen sensor monitors the amount of oxygen in the exhaust gas and helps regulate the fuel mixture. When the oxygen sensor fails, it can cause the engine to run rich or lean, which can trigger the check engine light.
2. Spark Plugs: Worn-out or faulty spark plugs can also cause the check engine light to come on. Spark plugs provide the spark that ignites the fuel in the engine cylinders. When spark plugs are worn out or damaged, they can cause misfires, which can trigger the check engine light.
3. Catalytic Converter: A clogged or damaged catalytic converter can also cause the check engine light to come on. The catalytic converter helps to convert harmful pollutants in the exhaust gas into less harmful substances. When the catalytic converter is clogged or damaged, it can restrict exhaust flow and trigger the check engine light.
Possible Causes of Hard Shifting:
1. Transmission Fluid Level: Low transmission fluid can cause the transmission to shift harshly. Transmission fluid helps to lubricate the transmission gears and clutches, and it also provides hydraulic pressure to operate the transmission. When the transmission fluid level is low, it can cause the transmission to slip and shift harshly.
2. Transmission Filter: A clogged or dirty transmission filter can also cause the transmission to shift harshly. The transmission filter helps to remove dirt, debris, and metal shavings from the transmission fluid. When the transmission filter is clogged, it can restrict fluid flow and cause the transmission to shift harshly.
3. Solenoids: Faulty or damaged solenoids can also cause the transmission to shift harshly. Solenoids are electromagnetic switches that control the flow of transmission fluid. When solenoids fail or become damaged, they can cause the transmission to shift harshly or even not shift at all.
4. Transmission Control Module (TCM): A faulty transmission control module (TCM) can also cause the transmission to shift harshly. The TCM is the electronic control unit that manages the operation of the transmission. When the TCM fails or becomes damaged, it can cause the transmission to shift harshly.
