2008 e320 Mass Airflow sensor location?
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Joined: Aug 2011
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2008 E320 Bluetec
Got intermittent check engine light and code p0402. Dealer ran STAR diag. and it recommended replacing component Y27/9 (left egr positioner). Not sure what that is exactly. I removed the EGR valve and cleaned it, but many resources online suggest this code usually isn't the EGR but rather the MAF (or a number of other random issues that throw this code). CEL is off right now, but I have no doubt it will return. Just trying all DIY cleaning options in hopes of saving my kids college fund.
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Joined: Jan 2012
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From: PA, USA
2004 E320 4matic Sedan
What P0402 means....
EGR = Exhaust Gas Recirculation. The EGR valve sends some small amount of the exhaust gases for a second trip through the engine. The relatively-inert exhaust gases cool the combustion chamber and reduce the amount of nitrous oxide pollutants.
The P0402 codes means that the EGR valve is allowing too much exhaust gas to flow into the intake manifold - or there is some situation that makes it look that way. I don't know exactly how this engine's computer monitors the EGR, so I am not sure if the code is absolute gospel or can be a false indication. If the car runs a little rough, that may indicate the code is genuine.
PS...There are plenty of codes that would tend to implicate the MAF(s), but P0402 isn't really one of them
PPS....YOUR issue has nothing to do with the crankshaft position sensor either
The P0402 codes means that the EGR valve is allowing too much exhaust gas to flow into the intake manifold - or there is some situation that makes it look that way. I don't know exactly how this engine's computer monitors the EGR, so I am not sure if the code is absolute gospel or can be a false indication. If the car runs a little rough, that may indicate the code is genuine.
PS...There are plenty of codes that would tend to implicate the MAF(s), but P0402 isn't really one of them
PPS....YOUR issue has nothing to do with the crankshaft position sensor either
Last edited by ozusa; Dec 22, 2012 at 09:53 PM.
Thread Starter
Newbie
Joined: Aug 2011
Posts: 11
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2008 E320 Bluetec
Car runs great. That's why I don't think just replacing the EGR valve will do it. I'm still having trouble finding out what Y27/9 (left egr positioner) is or where it's located.
