Last night the CEL came on, and I got the codes read on the way home.
- P0122: Throttle Position sensor "A" circuit low voltage
- P0139: Secondary HO2S12 (heated oxygen sensor - bank 1 sensor 2) circuit slow response
- P0420: Catalyst system efficiency below threshold bank 1
- P1456: EVAP emission ctrl sys leak detected (fuel tank system)
Then this morning the battery was very low and door locks barely worked. Checked voltage at the battery terminals and only got 8-9v. This makes me suspect that there is an electrical problem, possibly a bad alternator or battery. I'll check the age of the battery later and update this question.
I checked the obvious stuff (the gas cap was on) but can also check the throttle sensor once I get a jump start again.
I accidentally let the battery go flat about a month ago after leaving the lights on too long working in the dark. Lights got dim and car needed jumping. Could it just be a weak/old battery causing all this?