Toyota Repair: engine light, jumper wire, toyota camry

Question
1999 toyota camry 4 cyl. (bought it used with 36k) recently had block replaced due to clogged ports. the day we got it back the engine light went on, had to replace the sensor. after a month or so, the
engine light is back on again. car seems to run fine though.

what causes the engine light to go on? what can I check to fix it?


Answer
What makes that light come on, Answer= anything to do with the emissions.  Ok 1st we need the code or codes for you to get them raise the hood look near the firewall pass side for data link connector open the cap look in the cap you will want to study this ,take a jumper wire and jump TE1 & E1 don't let the wire touch any body part turn key to on, don't start look at the check eng light it will flash the 1st set of numbers then pause then flash the sec set a long pause means thats all and will start over (EXP:FLASH 1234 PAUSE FLASH 1234 PAUSE FLASH 123456 = 446 or go to autozone and they will check it for free at dlc 3 under dash with scan tool. If you do the autozone thing try and get a look at the code or codes on the scan tool and write them down.  Being the eng was out a vac line may be off or on the wrong port if you look and study  the vac routing you may find they have one backwards(vac routing under side off hood) there is one that goes to the EGR VSV on the back side of the head, you will have to look at this one from the pass side tire(turn wheels to left) and there is also the knock sensor on the block one wire make sure it's pluged up, Gas cap left loose or not sealing Po440,po446& po442. To reset the light remove the NEG battery cable wait 90 sec then replace and tighten or key off in hand pull the 15amp EFI FUSE under hood driver side fuse box, wait 90 sec reinstall fuse all codes cleared. usly if it's a sensor the light will come on after being reset if it's the evap system it takes two trips after monitor runs, clear codes drive for 15 mins park wait 5 mins drive for 15 mins light should come on evap/egr code should be set. Hope this helps.