What causes an OBD2 code of P0402 on a 2002 Ford Ranger and how do you repair it?

Answer 1

Changing the EGR valve on a Ford RangerAccording to the "Automotive Computer Codes" Techbook by Haynes a P0402 code is a: "Exhaust Gas Recirculation circuit, range or performance problem". This is normally known as the EGR valve.

Assuming that the EGR valve is the culprit of your problem -The EVP sensor (EGR valve position sensor) could also be the problem. Replacing the EGR valve should take care of that.

-Keep in mind that 2002 3.0L engines are NOT equipped with an EGR valve, therefore I'm talking here about the 2.3L, and 4.0L.

Anyway, here is how to change the EGR valve.

1. Disconnect the negative battery cable from the battery. 2. Remove the air cleaner outlet tube. 3. Disconnect the EGR valve vacuum hose (if equipped). 4. Disconnect the EGR valve exhaust manifold tube. On 2001 2.3L engines and later, remove the coolant Plumbing to the EGR valve. 5. Remove the EGR valve retainer bolts and EGR valve from intake manifold, or intake manifold EGR tube. 6. Remove the EGR gasket and clean the manifold of any remaining gasket. 7. Installation is the reverse of removal.

NOTE 1: When buying a new EGR valve, make sure that you get the correct one. Use the stamped code located on the top of the EGR valve when purchasing it.

NOTE 2: This information is also usefull for the Mazda B2300, B2500, B3000, B4000 from 1994 thru 2005.

Honda Man's AnswerThe E.G.R. can be checked with a hand vacuum pump. With the engine off attach the vacuum pump to the E.G.R. and apply vacuum, if it holds vacuum the diaphragm is good. With the engine running apply vacuum and the engine should stumble. The most common cause of the P0402 (Excessive E.G.R. Flow) code on any Ford is the DPFE sensor. Ford has had a problem with the DPFE causing the P0402 code. The first design was made of aluminum that corroded easily, the replacement is made of plastic which is somewhat better. For future reference OBD II codes can be looked up at DenLorsTools.com in the Tech Article section. When replacing the DPFE, check the condition of the rubber hoses, if they are ok use compressed air to clean before installing the replacement part. If the rubber is too dry and cracked, replace them with the with correct type of hoses (special DPFE hose).