850 stays in open loop, no codes, frustrated

guambrocha · Post by **guambrocha** » 28 Nov 2012, 18:17

1996 volvo 850, still cannot pass smog. According to mechanic it is not going into closed loop. O2 sensor has been recenlty replaced about 1 month ago. Any tips? dont know anything about this one.

Cheers and thank you

Post by **Ozark Lee** » 28 Nov 2012, 18:40

What codes numbers are being posted by the OBD-II? We need the actual Pxxxx numbers, not whatever the auto parts store says will cure the problem.

...Lee

guambrocha · Post by **guambrocha** » 28 Nov 2012, 18:55

There are no codes, the only time the check engine light turned on was a P0410, other than that none, very frustrating

Post by **Ozark Lee** » 28 Nov 2012, 20:10

Inspector Gadget may be referring to the readiness monitors. The monitors are exceedingly difficult to get set on a Volvo but there is a drive cycle that should help them to show OK.

This thread has the drive cycle and other information:

https://www.matthewsvolvosite.com/forums ... 6234#56234

...Lee

guambrocha · Post by **guambrocha** » 30 Nov 2012, 11:58

Thank you Lee. Intresting enough mechanic said he pulled codes p0410, p0442, p0446. P0410 was the only code my reader picked, replaced check valves (both) check airp pump: works just fine. Changed PVC and found a completly clogged with solid oil vacumm hose that cracked when I removed it (vacumm hose form flame trap to vacumm tree) no EGR to clean but I took it out and cleaned throttle body anyway and reinstalled with new gasket. After I repalced this code P0410 never came back, drove the car for over 2 weeks (city and freeway). Somoged it and NO up and beyond the sky. Mechanic stated car is not going into closed loop and picked the codes mentioned above even though no check engine light was seen. He reseted the codes, car went into closed loop and NO are now normal. I guess ill do the drive cycle and smog it and see what happens, ill post and see if it passed. Any thought?