Evap Emissions System Pressure Sensor

eriscentro · Post by **eriscentro** » 28 May 2012, 08:48

Hey guys, does anyone know of the evap emissions system pressure sensor on a 96' 850 base? I have a CEL (P0450) for the sensor, but I have no idea where to start the diagnoses. I can't find much about it in VADIS either. I'd really like to be able to fix this one myself instead of taking a trip to the dealer because I can only imagine how expensive it'll be to fix it. It's quite important at this point because it's preventing me from passing NJ's inspection.
Side note: There's also a CEL p1308. the longitudinal acceleration sensor
-Thanks, Ben

Post by **Ozark Lee** » 29 May 2012, 17:21

The most common cause of the P0450 code is cracked or broken lines from the gas tank - usually right at the tank itself. A bad gas cap can cause the same thing and you should be able to get it pressure tested at a chain auto parts store.

...Lee

eriscentro · Post by **eriscentro** » 29 May 2012, 18:55

The cap passed NJ Inspection, but the sensor was an issue. Would having those lines on the tank be cracked require the tank to be dropped to be repaired, or is that a relatively simple DIY job?

Post by **jimmy57** » 29 May 2012, 19:30

Unplug the vertical acceleration sensor up under the plastic cowl cover just in front of windshield. The accel sensor can fail and kill the 5 V ref voltage that the tank press sensor uses. The code you have is not for the lines usually it is for the sensor signal being out of range.
If the VAS is unplugged and the TkPS code clears and doesn't return you have your answer, VAS needs to be replaced.
The VAS is used so the ECM can rule out bad roads and wheels bounce as the reason the flywheel rhythm is irregular. Irregular flywheel rhythm is how misfire detection system is detecting misfires.
If the TkPS code stays then it could be the TkPS that is the bad guy.
Of course there is the monitor Vref signal and discinnect VAS and then TkPS to see if either is dragging down Vref.

eriscentro · Post by **eriscentro** » 29 May 2012, 20:13

TkPS code? I had actually just taken the cowl off, as the emissions sensor was on before the acceleration sensor. I unplugged the sensor, cleaned the contacts, and retaped the connection. I cleared the codes w/ it off, still had errors, although there was voltage coming in. The VAS is undoubtedly bad, given that the fault codes don't go away w/ it unplugged, cleaned, etc.

eriscentro · Post by **eriscentro** » 29 May 2012, 20:17

I'd check the TkPS, I am just unsure of its location, and model number. I have been unable to find much on the TkPS, and the specific 0450 code. It'd be fantastic if I could do the work myself to fix it instead of have to take it to the dealer. I'd try, but I have no idea where the sensor even is.

eriscentro · Post by **eriscentro** » 06 Jun 2012, 17:39

bump?

mattconrad850 · Post by **mattconrad850** » 30 Jun 2019, 08:10

eriscentro wrote: ↑28 May 2012, 08:48 Hey guys, does anyone know of the evap emissions system pressure sensor on a 96' 850 base? I have a CEL (P0450) for the sensor, but I have no idea where to start the diagnoses. I can't find much about it in VADIS either. I'd really like to be able to fix this one myself instead of taking a trip to the dealer because I can only imagine how expensive it'll be to fix it. It's quite important at this point because it's preventing me from passing NJ's inspection.
Side note: There's also a CEL p1308. the longitudinal acceleration sensor
-Thanks, Ben

on 850's its in front, behind bottom of radiator attached to subframe slight right hand side, you'll see the connector, it's kind of squarish made by Bosch