Have you looked at scan data for the o2 sensor? Does it toggle rich/lean? If not...have you tried forcing it rich/lean to see if it reacts? Almost sounds like an open in the 02 signal circuit which would put the signal voltage at roughly 450mv. From Alldata:
SYMPTOM
P0134-1/1 O2 SENSOR STAYS AT CENTER
WHEN MONITORED
Engine running for greater than 121 second. Coolant Temperature greater than 66 °C (150.8 °F). Engine in closed loop fuel control mode.
SET CONDITION
O2 signal voltage is between 0.35 volt and 0.58 volt for a total of 30 seconds and than O2 signal volt is 1.5 volts for 60 seconds. One trip fault.
Just got back from running it over to my best friend's house and he put it on his Snap-on scan tool.........not good news. He thinks the ECM got zapped because at first we had a flat line on the scan tool for the upstream then a spike to 3.9-4.0 VOLTS on both O2's
After clearing the code and about another 1.2 miles of road test time we got the same voltage 4 volt spike . The upstream gave the strangest info, while the downstream was perfectly normal. Then the voltage spike to 4.0 volts and the downstream went flat and nothing and the check engine light. Then the downstream came back to a normal graph/signal while the upstream stayed flat......
Dcuda69 thanks for the info and funny thing is my friend rattled off the very same info as the SET CONDITIONs that you posted like he knew it off by heart. And all of the rest of the info you posted was displayed on the Snap-on scan tool too. Thanks again.
And thanks Grizzly for your info too you were pretty much spot on with the voltage spike issue....still happening
Mike
