1989 Cadillac Deville with a "E48 EGR System Problem Code"


Asked by Aug 10, 2012 at 07:15 PM about the 1989 Cadillac DeVille

Question type: Maintenance & Repair

1st year Auto Tech student with a 1989 Cadillac Sedan Deville 4.5L V8 and a "E48 Exhaust Gas Recirculation System Problem Code" - My "Service Engine Soon" light comes on but not until i have driven it about 15 to 20 miles. I think it might be an exhaust leak and i just wanted to see what anyone else thought on what it  could possibly be? And is there any "proper" way to test an EGR Valve? Just in case that is what the problem is

1 Answer


First, check your vacuum hoses for the EGR system. If they are ok see if you can get your finger inside where the rubber diaphragm is. If you can, with the engine running at idle, press up hard on the diaphragm with your finger. This opens up the EGR valve & the engine SHOULD stall. If it stalls, the valve is sealing properly & the EGR passages are clear. You can do the same test using a hand held vacuum pump. Just disconnect & plug the vacuum hose at the EGR valve. Hook up your hand held vacuum pump directly to the EGR valve & pump it up. Again engine should stall. If the engine keeps running that means your EGR passages are clogged. You'll need to remove the EGR valve & clean these passages completely. Use a new gasket when re-installing your EGR valve. HTH. -Jim

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