Help. P0135 and P0155 codes returning after clearing replaced front O2 Sensors on 2003 dicovery same codes comming back O2 Sensors were Bosch universal. checked fuse#2 ok the connectors were full of oil from valve cover leak (fixed) washed them out with a cleaner but codes still return.Can anybody help

 

Are you sure you got all the oil out of the 2 connections, did you use electrical contact cleaner?

 

Front sensor heater LH bank - short/open circuit

Front sensor heater RH bank - short/open circuit

Your very own copy of the RAVE has these on page 331. The ECU looks at the heater circuit to see if it is functional, so the O2 sensors can be rapidly heated on a cold engine. It does this once each time the engine is run after some stabilization. The code could indicate an open or shorted or grounded or loose wire, or bad connection, and maybe even heater part sensor out of specification. Here is a page from the Bosch ECU manual that gives the exact data. This code takes two driving cycles before it will pop back up, so don't celebrate until clear for several days.

 

Mike Thank's not sure I used a solvent for cleaning grease etc off brake systems and blew out with air so i will have to check see if they have dried out they were pretty well soaked in oil.

 

I cleaned and dried the connectors for both o2's thoroughly checked operation both cycling up and down with even wave patterns but re checked codes and both came back as pending heater circuits

 

could i have 2 faulty O2 sensors?

 

Did you wire the plug yourself with all the wires?
Or did you get the Bosch sensors off of Amazon all pre-wired?

Check the heater circuit fuse too.

 

I rewired the o2s and solderd them to the origional plug wires

 

checked all the fuses under hood the only one blown was a 40amp for cooling fan i replaced that and as soon as the fan came on it blew so yep a new fan needed

 

UpDate the 2 universal O2s heater circuits did not warm up fast enough for the ecm. therefore kicked in the codes. swapped one O2 for OE Direct fit Bosch that side cleared and has stayed clear. Swapped the other. O2 problem resolved no more codes. Thanks again for the input.