shaneomac1602 Posted December 7, 2009 Share Posted December 7, 2009 so i have a CEL for my rear O2 sensor. i have already disabled the rear O2 and wrote it to the ecu twice. about 20 mins worth of driving later it comes back on. i hook up my laptop and read the ecu, check the diagnostic codes and the rear O2 (P0420) is no longer disabled. any ideas what im doing wrong? heres my process: 1)connect test plug (green plug under dash) 2)hook up OP 2.0 cable 3)put key in and turn to on position (fans begin cycling) 4)connect to ecu 5)read from ecu 6)open diagnostic codes 7)check the box for the rear O2 (P0420) (a little window opens saying the code is disabled) 8)i write to ecu 9)it says write complete 10)turn key off 11)un hook OP 2.0 cable 12)unplug the test plug then i turn the key back on, start the car, the CEL is gone. i go for a drive for about 20 mins across town, it comes back on. any ideas??? i really want to get rid of it. thanks for any and all help Link to comment Share on other sites More sharing options...
Spec B Posted December 7, 2009 Share Posted December 7, 2009 Sounds like you are flashing correctly..are you disabling the code via romraider? If you are using RR are you saving the new map (with the code disabled)? Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 7, 2009 Author Share Posted December 7, 2009 I am using ecuflash Link to comment Share on other sites More sharing options...
rtbrjason Posted December 7, 2009 Share Posted December 7, 2009 You have to save the rom with your changes prior to flashing it. You can do that in RR or ECUflash. Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 8, 2009 Author Share Posted December 8, 2009 Just save it to my laptop or where? Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 9, 2009 Author Share Posted December 9, 2009 anyone? where/how do i save it? do i have to write it to the ecu, then save it to the ecu? i assumed writing it to the ecu would be all it took Link to comment Share on other sites More sharing options...
Spec B Posted December 9, 2009 Share Posted December 9, 2009 With RR you save it to somewhere on your pc's hardrive then you open it up with ECU flash and flash it to the ECU. Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 9, 2009 Author Share Posted December 9, 2009 ok, ill give that a shot tonight. hopefully i get it right this time. haha Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 13, 2009 Author Share Posted December 13, 2009 so im in my car right now, read the ecu, disabled (P420), saved it to my laptop, then opened it up and the code is no longer disabled. wtf? i check the box, but its like its not staying. what do you think? would like to get this done as its cold out here. lol Link to comment Share on other sites More sharing options...
rtbrjason Posted December 13, 2009 Share Posted December 13, 2009 While not connected to the car, open the rom image you downloaded in RomRaider ECU Editor. Find and disable the code on the left hand side. Save this rom image (preferably with a new name). Connect to car and open ecu flash. Open the rom that you just saved and write that to ecu. Link to comment Share on other sites More sharing options...
shaneomac1602 Posted December 14, 2009 Author Share Posted December 14, 2009 oh, so i have to disconnect from the car then disable it, then reconnect. i got it. i have been downloading the rom from ecu flash. i dont know why my rr ecu editor isnt working properly, i have all the ecu definitions downloaded. when i try to open a rom with RomRaider which i downloaded and saved with ecu flash, RomRaider says "ecu definition not found." which doesnt make sense. i tried downloading the newest version of the definitions, but i already have the latest versions. Link to comment Share on other sites More sharing options...
siegelracing Posted December 16, 2009 Share Posted December 16, 2009 Just use ecuflash to edit the map. You'll have to click on the "enabled" button and press the minus key - it should then show disabled. Save that map. Then flash it. Siegel Link to comment Share on other sites More sharing options...
rtbrjason Posted December 16, 2009 Share Posted December 16, 2009 ^ Agreed. If you can't get RR to work, you can edit the rom with ECUFlash. Just make sure you're saving the rom image (preferably with a new name) and then flashing that newly saved image. I think this was the step you were initially missing. Link to comment Share on other sites More sharing options...
kewshi Posted February 1, 2016 Share Posted February 1, 2016 So will doing this actually help someone like me with a p420 code? Link to comment Share on other sites More sharing options...
Thinking out side box Posted March 31, 2016 Share Posted March 31, 2016 sensors still go bad, I had to replace both of mine at the same time to fix a similar issue i'm a mechanic, but that is what that code says Link to comment Share on other sites More sharing options...
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