1998 S70 CEL (Back to the dwg. board)

Mr. Detail · Post by **Mr. Detail** » 22 Jul 2014, 15:51

O.K. Just finished over the weekend replacing that small rubber 90 degree elbow beneath the upper radiator hose and the end of the manifold. That was a bear for me to remove & replace while not removing the manifold.

After replacement I cleared the code with my OBD2 reader and was hoping for the best. After about 75 miles of driving, the CEL is back on again.

I connected my reader and pulled the same, good 'ole code of P0133. As I said in another post, I have already replaced both front and rear oxygen sensors last year.

Any more thoughts before I take this car to a diagnostic computer?

Post by **Ozark Lee** » 22 Jul 2014, 16:14

When you replaced the sensors what did you install? If they weren't OEM Bosch (not the universals Bosch) then that may be the problem. The vacuum leak at the elbow usually throws a P0127.

...Lee

Mr. Detail · Post by **Mr. Detail** » 23 Jul 2014, 05:10

Mr. Ozark,
I replaced the front sensor with a O.E. Bosch and the rear one with a NGK.
I had one of the various indy shops last year tell me that they had trouble with Bosch and lots of luck with the NGK's. At this point, I don't know what or who to believe.

So are you saying for sure that if I went out and bought another new O2 sensor (Genuine Bosch) that my CEL will go out?

Post by **rmmagow** » 23 Jul 2014, 06:50

Nothing's for sure with an old Volvo. Start checking other rubber bits, check the condition of the Air Pump system. I got the similar code when my SAS system had hose issues. I replaced the whole thing, pump and small rubber lines, a one-way valve etc. Make sure you have no exhaust leaks at all. You might want to have the car connected to a very good diagnostic machine where they can watch the voltage fluctuations on the front and rear O2 sensors. Front should oscillate a lot, the rear not so much. If the rear oscillates a lot too, possible crapped out CAT.

Mr. Detail · Post by **Mr. Detail** » 23 Jul 2014, 13:00

A fellow Volvo friend of mine at a different forum found a post here from back in 2009.

In the post, the guy "pkc303" spoke of a vacuum line that runs from the vacuum tree just above the idle air controller over to a fuel damper just under the fuel rail.

Can you help me find a photo or screen shot of where the heck this is?
He said the elbow was deteriorated at this point of contact. He replaced that elbow and the CEL stayed out after driving 70 miles.

Post by **abscate** » 23 Jul 2014, 19:18

Fuel pressure regulator or FPR

That should give lots of search hits