Here's a breakdown of likely culprits:
* Low Oil Pressure: This is a critical issue. Low oil pressure can damage your engine very quickly. Causes include:
* Failing oil pump: The pump might be wearing out, unable to maintain sufficient pressure.
* Clogged oil filter or pickup tube: Restricting oil flow.
* Low oil level (despite your check): Even though you think it's okay, a faulty dipstick or inaccurate reading is possible. A leak is another possibility.
* Worn engine bearings: This is a severe problem, and low pressure is a symptom, not the cause.
* Transmission Staying in Low Gear: This suggests a serious transmission problem. The overfill *could* be contributing to this by causing excessive pressure and potentially damaging internal components. However, it's more likely a symptom of a larger problem:
* Transmission control module (TCM) failure: The TCM controls shifting. A malfunction could cause it to stay in low gear. A related code should be present in the check engine light.
* Transmission valve body problems: Internal valves controlling shifting might be failing.
* Low transmission fluid (despite overfill): Again, a faulty reading is possible, or internal leaks might be masking a low level. The overfill could indicate a leak *somewhere* in the system.
* Internal transmission damage: Worn gears, clutches, or other internal parts can cause the transmission to malfunction.
* Check Engine Light: This confirms that the car's computer has detected a problem. You *absolutely* need to get the codes read from the car's computer using an OBD-II scanner. These codes will pinpoint the exact problem(s) the computer has detected.
What to do immediately:
1. Do NOT drive the car: Continuing to drive with low oil pressure will severely damage your engine.
2. Have the codes read: An auto parts store often offers this service for free.
3. Check the oil level again: Use the correct procedure for checking oil in your car. Make sure the car is level and the engine has been off for a few minutes.
Once you have the codes: You will have more information to determine the specific cause. It's highly likely that you'll need professional help to diagnose and repair the issues, especially concerning both the engine and transmission simultaneously. The combination of low oil pressure and transmission problems suggests a potentially catastrophic failure.
The overfilled transmission fluid is a concerning detail, but it is a symptom, not the root cause. The other problems are far more serious. Ignoring this could lead to very expensive repairs or even a need for a replacement engine or transmission.
