codes PO136, PO137,PO455

jljholmes · Post by **jljholmes** » 24 Mar 2010, 05:31

Here's the story. CEL is on for about 3 months. Pulled codes PO136 and PO137. Both Bank 1, Sensor 1. SEnsor Circuit Malfunction and Sensor Circuit Low Voltage respectively. So I figured I'd wait till better weather and change the rear O2 sensor. So I did that last week and cleared the codes. After 5 minutes of driving time on comes the CEL again and now the codes are PO136 and PO455 (evaporative system large leak). Anybody know where to go from here? Any help will be really appreciated. BTW I replaced the rear O2 sensor with the original Bosch with the correct pigtail ( no cutting or crimping involved) from FCP.

JLJHolmes

jljholmes · Post by **jljholmes** » 24 Mar 2010, 05:44

Sorry, I just checked my invoice from FCP and the O2 sensor is a Walker. it is the only one they list for the non-turbo 1999 V-70 All the turbo models have an NSK sensor. No Bosch units insight. Do not know if this helps explain anything. Thought I better let everyone know. Thanks.

JLJHolmes

Georgeandkira · Post by **Georgeandkira** » 24 Mar 2010, 06:32

Hello, Where did you look up the codes? Decoding 3 of these doesn't make me an expert but I thought "Bank 1, Sensor 1" would be the front sensor-the one upstream of the catylitic converter. Regarding the large leak: Start looking for a disconnected hose; perhaps near where you were working. Has anyone on this board used a piece of inner tube with its valve to pressurize at the filler neck and maybe hear a leak? Would the purge valve(s) let you do this? Kira

jljholmes · Post by **jljholmes** » 27 Mar 2010, 04:46

Boy do I feel dumb. You're right. I did say sensor #1 in my original post. That is incorrect. It was Bank 1 sensor 2 for both codes. I replaced the rear sensor only. Hope this clarifies somewhat.