EGR Valve

Hello,

The EGR valve is located at the front of the engine on the right side but only some had it this year. Here is a video to show you how to test it. You should know that some do not have an EGR valve. There is no egr valve on any of the 02 Chevy or gmc 5.3 engines

https://youtu.be/DqUCbbKdWf4

Check out the diagrams (Below)

Please let us know if you need anything else to get the problem fixed.

Cheers

Engine Performance problem
2002 Chevy Tahoe V8 Four Wheel Drive Automatic 77000 miles

My tahoe was doing the rough idle/ nearly stall problem and threw a p0170/p0174 code, so I replaced the MAF sensor. After installing the sensor it also threw a p0300 code. I cleared all codes and disconnected the battery for a couple of minutes. Since then I haven't noticed a rough idle except when below freezing outside untill the engine warms up. There have been no new codes. No vacuum leaks that I can find. The current problem is horrible gas mileage.Like 8 to 10 highway. Fuel pressure is good, new plugs and wires so I am suspecting egr valve (I have seen that on 2 previous GMs Ive owned) I removed the intake cover but can't find the egr valve anywhere. Where the heck is it? 5.3L VIN code T

Hello markvdb hope this can help, Pin Wire Color Circuit No. Function A WHT 257 Exhaust Gas Recirculation (EGR) B PPL 719 Sensor Return C BRN 1456 Exhaust Gas Recirculation Solenoid Position Signal D GRY 596 Reference Voltage Feed (5 Volt) E RED 1676 Exhaust Gas Recirculation Solenoid Feed

location:

I was wrong, it is an engine code Z. Evidently it doesn't even have an egr valve. Back to the drawing board.

Hello,

P0170
P0174
The 2 codes point at the oxygen sensors,
What you should look again is for vacuum leaks - check for failed or loose vacuum lines, leaking intake gaskets, intake air tubes loose or any other source of un-metered air leaks (leaks after the Mass Air Flow Sensor)
2. Restricted fuel filter or bent/pinched fuel system lines (the last one could happens when jacking the car up on fuel line)
3. Incorrect input from other sensors, such as the Mass Air Flow Sensor wiring, which may not always drop a separate code
4. Engine misfire –. You might think that if there is a misfire then you will have all that unburned fuel and it should read rich; right? Well the O2 sensors read only oxygen content in the exhaust, so if you have all that unburned fuel from incomplete combustion then, you guessed it, you also have all that unburned oxygen. High O2 content in exhaust equals a lean reading!
EGR system will typically set a separate code. A leak in the exhaust system before the O2 sensor will also cause incorrect readings. And always check for after- market modifications. These can throw a wrench into the works! The only other possibilities (however unlikely), are wiring issues, computer concerns or a bad O2 sensor.

I guess the next step is O2 sensors, although it hasnt thrown any codes for nearly 3 months. Runs ok except a little on the weak side power wise on acceleration and the bad gas mileage. Question is, which O2 sensor to start with? I've cleaned the throttle body plate, there was a layer of tar-like garbage behind the plate.

Hello P0171 is on bank 1 Bank1 is the side with the cylinder #1 P0174 is on bank 2 on the other side. Here is the diagram,

I have a marker on the side where the bank 1 is, oxygen sensors on that side. Code does not say" sensor 1 before the catalytic converter and sensor 2 after the catalytic converter So is the code p0174 on the other side. Not all the oxygen sensors fail same time. Have the injectors cleaned (walmart is cheap) check for vacuum leak around the intake.

Which sensors generally go bad giving the P0171 or P0174 code, before or after the converters?

If Short Term + Long Term Fueling > 25% FOR TIME > 100 SEC.
P 0171 is set.
your sensors are good,check for vacuum leak around the intake

markvdb,

Did you solve your issue? My Tahoe has recently started to exhibit the exact same problems you have. I am about to replace the intake manifold gasket.

Thanks

Engine Performance problem
2002 Chevy Tahoe V8 Four Wheel Drive Automatic 77880 miles

Every diagram I've seen on my 02 Hoe (VIN Z) 5.3L shows an egr valve attached to a tube coming off of the passenger side exhaust manifold. The exhaust manifold on mine has a solid end. No tube, and I can't find an egr valve anywhere. What's up. Did it not have one, or had the manifold been replaced in the 20k miles before I bought it?

hello and thanks for donating


yes the 5.3L should have an EGR valve at the top right front of engine, if it's gone then previous repairs must have been made, although i don't believe the vehicle would run very well without the EGR valve if it was originally equipped with it...

EGR Valve is located on top right of engine-see diagram below: There is no egr valve on any of the 02 Chevy or gmc 5.3 engines

I have a 2004 Tahoe LT 5.3 VIN"T" and bought it new and it does not have an EGR at the front location like everyone is saying.

Hello, I am Danny.

Was this the picture that was provided? See attached -as it should be on the right front valve cover (circled in red). Some do not have an EGR valve FYI. Hope this helps and thanks for using 2CarPros.
Danny-

I have a 2003 Tahoe Z71 5.3.
I've been experiencing horrible gas mileage, the digital indicator (miles until empty) fluctuates wildly. For example, it can be resting at 120 (miles), I drive 1 mile and it ticks down to 110 or below, then it may creep back up to 115, then when I park and put it into "P" it will climb up or down another 6, 7, 8 digits. The gas needle corresponds, so it appears the gas is being burned as opposed to a faulty sensor. I've replaced the throttle body (ACDelco with sensor), bank 1 O2 sensor, catalytic converter, PCV valve, spark plugs (ACDelco) and wires are less than 2 years old, and a new thermostat (ACDelco). Most recent codes show p0174. The thermostat was replaced twice (first was after-market) because it was stuck open and the engine was not reaching the proper temp, the new thermostat (ACDelco) seems to be doing the same, not reaching the 210 degree mark, only reaching about 180 or so. I believe there is also a small intake gasket leak. I would appreciate any help and advice I can get...tired of throwing parts at this thing.

Welcome to 2CarPros.

I hate to ask, but I need you to start a new thread regarding your question. Please just copy and paste it to a new thread. We are trying to keep questions separated.

I hope you understand.

Thanks,
Joe.

I have a 1999 Tahoe, the SES light came on and the truck quit running at idle. I had it read and it said something about a EGR system. I changed the EGR valve and it worked for about two monthes then started again. I thought maybe the EGR valve went bad again so I replaced it agian. This time it did not help but the truck will idle MOST of the time but the light stays on and the engine seems like it does not run as smooth as it should all the time. Is there another part to this circuit I should look at?

First thing you need to do is have the codes read, Autozone does it free, Post the results with the code number(s). Even if the service engine light is not on, there should be freeze frame data stored.

Are you getting an EGR code now. What is the code that you have.

Tahoe service engine soon lamp comes on after 10 minutes from cold start . ECG code is EGR trouble. 200K mile on tahoe changed EGR valve and solinoid.
Checked all vacuum lines. Lamp goes out after shut down and stays out from then on when warm.

When you replaced your EGR, did you disconnect your battery for several minutes. Sometimes you need to do this or the computer will still think it has a problem. On a side note, usually when an EGR goes it could be because of carbon fouling or the Temperature sensor may be bad. But disconnect your battery, I usually waite a 1/2 hr or so just to be sure. If the SES light comes back on have it check and if you have a P0400 or P040X then you know you for sure you have an EGR problem.
P0400 Exhaust Gas Recirculation Flow Malfunction
P0401 Exhaust Gas Recirculation Flow Insufficient Detected
P0402 Exhaust Gas Recirculation Flow Excessive Detected
P0403 Exhaust Gas Recirculation Circuit Malfunction
P0404 Exhaust Gas Recirculation Circuit Range/Performance
P0405 Exhaust Gas Recirculation Sensor A Circuit Low
P0406 Exhaust Gas Recirculation Sensor A Circuit High
P0407 Exhaust Gas Recirculation Sensor B Circuit Low
P0408 Exhaust Gas Recirculation Sensor B Circuit High

Thanks for the reply!
Yes I have reset the ECM. The only code in the ECM is 32 after 5 rounds of code 12. I am not familar with your P0400 or p040x code iformation,could that be using a code reader? I am shorting pins AtoB and reading the SES light.
This is the code information I have found so far.
32 EGR open command did not change the fuel mixture when the command was given during off idle operation. EGR opening should cause the mixture to be slightly richer because of the low oxygen content of the exhaust gas. EGR position signal is also monitored to verify EGR movement.
Do you know how in the last part of that the ECM gets a EGR position signal? There are no electrical connection on the EGR.
Where should I go next? I own another 95 Tahoe 2wheel drive and I am thinking of swapping the EGR componets now.
Thanks for your help
David

I have a 1996 chevy tahoe. I did the tune up by changing the rotor cap, distributor cap, plugs and wires.
I got 2 problems. First when i put the key in the ignition and crank it to start it i have to hold the key in start for about a second and a half, im wondering if that is normal for a tahoe or perhaps thers another issue with it.
Secondly the check engine light came on and after checking it with the ODB checker, it says that its is an egr problem. THat would explain why when idling the car sounds like its choking and not idling smooth, feels congested. I have been told that instead of spending $300 ++ on a new egr valve i could simply take out the one i have and try cleaning it. Will this solve my problem for the time being, seeing as to how in ontario we have emission test, and this wont allow it to pass. If I should try to clean out what do i use to clean it?

Egr valves recirculate exhaust gas. They do get carboned up and they can be cleaned. I use brake cleaner and it works great. But, with 286000 miles on the engine, it may be time for a new valve. Remove the valve and spray the inside of the valve -- you'll see all the carbon built up...Be sure to replace the egr gasket with a new one and do not over tighten the bolts -- they can strip easily, applying a little never seize to the bolts is a good idea.
However, the egr valve only operates at a certain temperature. The minor starting issue may be something else --- What is the fuel pressure?