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Randall C
Randall C, ASE Master Tech
Category: Cadillac
Satisfied Customers: 12719
Experience:  ASE Master Tech, 32 years exp,Cadillac 6 yrs
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Maf..manifold - it sounds like an intake manifol gasket leak

Resolved Question:

2002 Eld. pulling up codes PO101 +102 -( maf ) -PO121 - TSP & other related codes its been difficult to diagnos now I'm getting PO403 & 405 - EGR now the engine is racing which makes it difficult to inspect while running there is a loud suction leak sound which seems to be in the area of the EGR valve -- rear right hand of manifold - it sounds like an intake manifol gasket leak. I'd like input or other opinion before I pull it appart. Thanks Jimmy
Submitted: 6 years ago.
Category: Cadillac
Expert:  Randall C replied 6 years ago.
Hello, by your codes and description, i thing a pice of carbon is caught under th pintle of the EGR valve. This type of linear EGr was prone to this. To check, you need to unbolt the EGR and VERY slowly lift the EGR off the manifold. handle it very careful and turn it over and see if the pintle is stcuk a little open by a piece of carbon. The reason i say handle slow and careflu is because once you start bumping or handling the EGRm the carbon piece could fall out and you would not be able to confirm this is what happened put EGR back on and it runs ok. A vacuum leak from EGR will set low MAF flow, and o2 sensor codes. i would surely check the EGR first


  1. Disconnect the exhaust gas recirculation (EGR) electrical connector.
  2. Remove the EGR valve retaining nuts/bolts. IMPORTANT: Inspect the EGR passages in the crossover water pump housing for deposits. Clean the EGR passages as needed. Refer to Exhaust Gas Recirculation (EGR) System Cleaning.
  3. Remove the EGR valve.
  4. Clean the EGR valve mounting surface.

  1. Install the cleaned or the replacement EGR valve using a new gasket. NOTE: Refer to Fastener Notice in Service Precautions.
  2. Install the EGR valve retaining nuts/bolts. Tighten Tighten the retaining nuts/bolts to 24 N.m (18 lb ft ).
  3. Reconnect the EGR valve electrical connector.

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