invader

So I just got done installing new head gaskets last weekend in my daughters 93 runner with the 3VZE.

After working out an initial over heating problem, and a cam timing problem, everything seemed to be running fine for the last few days.

Last night my daughter came home and said there is a CEL.

Came up with code 71, EGR temp sensor. Today after work I am going to check out the EGR valve function but thought I'd ask what is commonly the issue with code 71. Especially since it was fine for a day or two.

Thanks,

Invader

GA22RE

Here's the skinny on Code 71. According to the FSM's the possibilities could include: 1) An open in the EGR gas temp. sensor circuit, 2) an open in the VSV circuit for EGR, EGR Hose Vacuum hose disconnected, valve stuck 3) Clogged EGR Passage. You will see the unit on the side of the EGR Valve. It has a Two-Pin Connector that connects to the wiring harness. Now obviously check your hoses and such but here is another thing you might want to consider. Did you clean out the TB or did anything get into the plenum while servicing? If no that's okay. I have seen alot of times when these things come to the dealer that the sensor has accumulated alot of carbon and buildup on the stem of the sensor. So here's the first test you can do after you have performed all of the preliminary checks. Take you DVOM or multi-and measure the resistance between the two leads of the connector going to the temp sensor. If engine has been sitting for a hour or so you should get a reading of about 69-89 Ohms. If the engine is at operating temp you are more likely to get a reading of about 16-10 ohms. Now getting no reading or a maxed out signal is one thing but use your judgement here. If it's off a little chances are that carbon buildup I was referring to has occured. Now taking a 12mm wrench is probably not going to be enough to remove the sensor since it's been through so many warm-up cycles and probably rusted. So you can use some penetrating oil and a flare-nut wrench (12mm) to remove the sensor (remember at this point you want to have the sensor disconnected). If you find that set-up will not work you can take a deep-well 12mm 1/4" socket and with a little creativity modify it a little. This is what I did for easy removal of these sensors. Picture an O2 sensor specialty socket. It has a slit in the side of the socket to leave room for the harness during removal / installation of the O2 sensor. Basically you want to mimic this with the 12mm deep-well. After removal inspect the stem of the sensor. You may have to clean the stem as deposits are sure to be there. Re-install and see if that take's care of it. Remember though the FSM's usually list in order of ease of diagnosing so don't forget your preliminary checks like the sensor connection, EGR and VSV operation as well as hose connections. This method I mentioned is just one I picked up after repeatedly coming across this code.