I was tinkering with an 850 N/A today that had a few codes. P0326, P0331, and P0444. I know the first 2 codes are for knock sensors but can't figure out what the last code is for???

 

If thats from the ODBII Port.. That sir is a Low evap Signal..


OBDI port under the hood, 444 is acceleration signal.

 

Low evap signal. It was taken from the OBD-II port. What does that mean?

 

That is EVAP Valve signal too high. It seems all these codes point to the fuel pump.

 

Fuel pump? The car is running great. The catty is gone but other than that it runs good.

 

Knock sensors, evap codes -- these are some of the random codes thrown by the fuel pump. Have you driven it up on hills 50-60 mph?

 

0444 is low signal, 0445 is high signal..

What about the cracked hose issue on the fuel tank?

That would throw the evap code if its sensing low fuel vapor
could be a bad fuel cap also

Evap is supposed to be a closed loop system.
If there is a leak it will throw a code.

I learned this in jersey when I failed inspection twice

 

Check this out...

EVAP System Operation - YouTube

 

EVAP leaks trigger other codes (such as "large leaks", or "small leaks"). Based on programmed logic, ECU controls the EVAP Valve. When such valve returns voltage outside the pre-determined range, at several occurrences, then ECU illuminates the CEL with a permanent fault.

That's not my point however. If you got multiple codes, that deal with misfires or fuel system, they just don't tend to be coincidences. They usually have a common fault.

By the way Matt: what are you using to interpret codes? This is my document.

 

I just found this info on Matt's site: http://www.matthewsvolvosite.com/for...hp?f=1&t=34737
Seems to make some sense. I'll check those vacuum lines and go from there.

 

I was getting mine from a list I found on VS a long time ago...

Herehttps://docs.google.com/document/d/1.../edit?hl=en_US

PS I wasnt saying you were wrong, I was just sharing my experience...

 

I googled "P0326 + P0331 + volvo" and hit this thread; ha!

RSPI: this is '95 so you should be able to pull the corresponding DTCs too (reading the LED port under the hood); in the thread above are diag procedures for cking the knock sensors. I assume you already tried resetting the codes and see if they come back?

Also i remember there was an update or recall for the knock sensor harness or something on early 850s but couldn't find a link quickly; thought it was fixed on '95s but i could be wrong.

Henry: that's the first I've heard of associating knock sensor codes to a bad fuel pump; could you explain that one?

 

I am not 100% sure how Volvo/Bosch programmed the ECU; that logic is proprietary. I do know that when fuel pump cannot deliver the sufficient pressure, especially at WOT, knock sensors can detect this out-of-range pressure / combustion / compression and and ECU interprets that as a Knock fault.

In my own experience, when my fuel pump was failing, I did get knock sensor faults. Other times, I would get misfire codes too.

I am not sure if for rspi is the fuel pump. But surely, simultaneous faults are not coincidences. They usually have a common cause.

 

I flirt around E a lot and one day I was sitting in front of a friends house and didn't realize I was on a slant. Well, the car ran out of gas and stalled. When it did, it tossed about 12 codes. LOL, I got the car moved a little and it started so I went and put gas in it. I really was surprised how many codes running out of gas tossed.