My Honda Civic has 119k miles on it. Recently, the check engine light came on, and the car immediately started experiencing 2 problems. First, when I'm at a stop light or in my driveway, the RPM get very low, close to zero, but the car has never stalled.

My second problem is that my engine all around feels less powerful than it used to, like the RPM have to get higher to do the same amount of work it would normally do. This causes the car to shift higher than normal, around 3.5/4 RPM. Sometimes if I'm on a hill the car will stay around 4-4.5 RPM and never shift until I step on the gas and gain some speed.

All of this happened about 2 days after I changed the oil. I havent had time to change the transmission fluid, but the dip stick says there is plenty in there and it doesnt look like its gone bad.

 

Waiting for next shoe to drop.

 

Check the CEL code first: https://honda-tech.com/forums/honda-civic-del-sol-1992-2000-1/how-pull-cel-d4-srs-abs-codes-code-lists-1901557/

Report back.

 

One of the codes was P0505, which has to do with the Idle Air Control system. The other was an oxygen sensor that had gone bad

 

What was the O2 sensor code? You benefit by sharing all information.

 

you need to remove and clean the idle air control valve and make sure the throttle position sensor has correct voltage.