View Full Version : Abnormal 01 A6 2.7t O2 sensor issue

05-10-2015, 09:46 AM
Hello ... I just rebuilt my turbos, installed a new zf torque converter, and did some other minor work myself ... Im no sloutch when it come to wrenching ... However my go to Aston Martin tech has passed and need a little advice ...
So ... Everything is stock and running fine except ... A reoccurring code/codes:
First i get P0135 ... Bank 1 sensor 1
Then a bit later after driving at reasonable pace PO155 Bank 2 sensor 1 (heater circuit) ... Yup got it
Here is the odd part ... I tested my O2 sensors at the correct heater leads with my OHMMETER and came up with values under 20 (7.9) which I have read are normal and if the O2 sensor heating was bad would read way beyond the spec.
QUESTION: what is the correct O2 sensor heating element OHM SPEC ? ... AND besides the clip itself is there any other possible influence that i can test before I start tracing my wiring from the O2 sensor clip back to the computer ... Coolant temp maybe as it is tied in??
I've heard that the harness may have notoriouse problems when moved around and or josseled which i did move around when working on the torque converter ...
Anyone have a good wiring schematic for the O2 sensor back to the computer ? Any tips would be much appreciated and i'll be sure to offer any advice with what i am now familiar with about 2.7t issues ... Thanks again.

05-12-2015, 01:55 PM
Uh oh ... Just pulled off the hwy and almost stalled ... Has a bad studder while acceleration and idle ... Engine light blinking ... I found the "SAI" hise unplugged on the drivers side and reconnected it ... Read and cleared codes and unhooked batt for a bit ... As of now still has the bad studder throughout driving and idling ...
Codes in order are as follows

Po304 cyl 4 misfire
Po155 02 bank 2 sensor 1
Po135 02 bank 1 sensor 1
Po2096 post cat fuel trim to lean bank 1
Po2099 post cat fuel trim to rich bank 2
Po237 turbo boost sensor A circuit low
Po106 manifold absolute pressure/baro sensor range/performance
.... I got to start somewhere ... Any ideas? The cat on he drivers side seems extra hot ... Would it throw these codes?? Maf sensor ? Any direction would be helpful as i will begin testing soon ...

05-16-2015, 03:41 AM
Well ... It seems that my #4 ignition coil pack is bad and also my pre cat is plugged ... I think im going to put a cheap chinese speed daddy 3" down pipe kit on ... Its supposed to be a direct fit ... We will see ... I got a ignition coil pack on the way for $31.00 from 1A Auto with a lifetime warranty!

09-06-2015, 05:44 AM
Well I'm im still having an o2 heater circuit issue ... I have cleared all codes except the two heater circuit codes. I have made piggies and added some bullet high flow cats ... New map and maf helped ... I am experiencing bad 12-15mpg and erratic shifting ... I have installed two new bosch o2 sensors ... They test good ... However i am only reading .6 volts for a power supply to the sensor connector from the computer (im assuming) i believe that the heater circuit to the sensor is supplied with 12 volts from the ecu directly and if I am not getting that power to heat the circuit than i can assume my ECU needs replacing... Right? We will find out ... I have already gone through the wiring harness and checked for any imperfections ... It checks out ... So im back to ECU replacement .... I havnt fiund a good schematic yet relating the 02 heater circuit to and from the ECU and any other related components ... Still have abnormal 02 senser issues ... Working 60+ hours a week so only have a little time on the weekends for relies and work on the vehicle ...