Check Engine Light has come on after been reset by mechanic (and no problems reported) 2 times in last month and a half and now just came on again. Heard there is a sensor (oxygen perhaps) that could go bad and cause false reads and the engine light to come on? any thoughts. Much appreciated. 1998 s70 with 85,000 miles.


-- Big Volvo Fan

False readings???? What code did your mechanic find? How many miles on your engine? It could be an O2 sensor, that will set the CEL and decrease your MPG.

Klaus
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

Thx Klaus, wouldn't the code for the check engine light read a bad 02 sensor? what is CEL by the way....seem to be getting poor MPG. 85k miles


Codes so far448 and 442 air pump and air pump system which checked out

EGR system code -- mechanic secured loose vacuum hose at air filter and reset faul t codes


THX

When you say the air pump and air pump system "checked out" what do you mean? Is your mechanic experienced with Volvo's? 442 and 448 are codes indicating there is a flow fault in the pair system (the air pump). Most commonly will be the SAS valve which allows fresh air to flow to the cat to help reduce emissions on cold startup. If the SAS valve is leaking, it will cause a CEL.

There are a bunch of other codes that a car will set besides the O2 sensor codes.

What about the EGR system code? 442 and 448 are not related to the EGR. Was there another code?

Are you sure the codes were not P0442 and P0448?

BB

CEL is shorthand for Check Engine Light. I don't have a 448 code listed anywhere. The vacuum hose is a definite problem, the air pump not working should not effect your milage, but will trip the CEL. Most CEL warnings are related to emissions stuff.
Clean the throttle body, check the tire pressure, make sure your tranny fluid is not dark brown, etc.

Klaus
--
98 V70Rawd(101Kmi), 95 854T(85K mi), 75 164E(173K mi)

My 1998 S70 T5 with 130k has the similar problem. Have to get a proper code reading. The light comes on every two week or so in the winter after reset with battery power-off.


Alex