dead battery caused weird problems
I am working on a 2007 jeep compass (2.4) for a friend. I accidentally left the key on overnight and ran the battery down. I connected my charger and recharged the battery. When I started the vehicle, I got a check engine light, a throttle (lightning bolt) light, and a traction control light. My code reader came up with P2004, a stuck intake manifold runner), a code about steering angle, and an ABS code C121C. The engine is in limp home mode and will not reset. I reset all the error codes, and calibrated the steering angle by turning the wheel left then right to the stops per the repair manual. I removed and checked the intake manifold runner sensor, it was not stuck, and re-installed it. I still get the P2004 error and the C121C error, the vehicle is in limp home mode, and the brake pedal is rock hard, but will barely slow the vehicle. I cannot press hard enough to slide the tires on a dirt road. The engine surges from about 1000 RPM to about 2000 RPM when idling.
Is this something that can be reset using a better code reader? The C121C code seems to indicate replacing either the PCM or the ABS module, both costing over $500 each! Did running the battery down damage all these components? Any ideas would be appreciated.