Got 0302 EGR System Hi/Low Flow Code, Need Help
11-09-2007, 10:19 AM
#1
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Join Date: Jun 2006
Location: New Haven, CT
Posts: 481
Got 0302 EGR System Hi/Low Flow Code, Need Help
I got 0302 EGR System Hi/Low Flow Code today.
I don't know where to start looking for a problem. Did anyone had this code and how did you fix it ?
I cleaned Throttle body and MAF sensor 2 weeks ago but it shouldn't affect EGR system.
Could it be a clogged small egr pipe ? (when I cleaned IACV a year ago I saw that the pipe opening is clogged but I had no codes).
I don't know where to start looking for a problem. Did anyone had this code and how did you fix it ?
I cleaned Throttle body and MAF sensor 2 weeks ago but it shouldn't affect EGR system.
Could it be a clogged small egr pipe ? (when I cleaned IACV a year ago I saw that the pipe opening is clogged but I had no codes).
0302
Diagnostic Trouble code 0302 points to a problem with the Exhaust Gas Recirculation system. The malfunction is detected by the Engine Control Module when no EGR flow is detected under conditions which call for EGR. Possible causes include:
- The electrical harness or connectors (valve circuit open or shorted)
- The EGR valve is stuck closed
- Weak or dead battery
- The EGR passage is clogged
- Faulty EGR temperature sensor circuit
- A leak somewhere in the exhaust system
The EGR Volume Control Valve may be tested with an ohmmeter. Disconnect the electrical connector. Looking at the connector half which is attached to the EGRVCV with the latch at the 12 o'clock position you will see two rows of three terminals. The top row is numbered 1-3, right to left. The bottom row is numbered 4-6, right to left. Measure the resistance between these terminal pairs:
2 1
2 3
5 4
5 6
... all resistance values should be 20.9-23.1 ohms at 68 degrees F.
Reconnect the EGRVCV connector halves. Turn the ignition switch ON OFF repeatedly. Verify that the EGRVCV shaft moves smoothly forward backward according to the ignition switch position.
The Exhaust Gas Temperature Sensor may be tested with an ohmmeter. The specifications are ...
- at 32 degrees F, 0.68-1.11 Megohms
- at 122 degrees F, 0.09-0.12 Megohms
- at 212 degrees F, 0.017-0.024 Megohms
Diagnostic Trouble code 0302 points to a problem with the Exhaust Gas Recirculation system. The malfunction is detected by the Engine Control Module when no EGR flow is detected under conditions which call for EGR. Possible causes include:
- The electrical harness or connectors (valve circuit open or shorted)
- The EGR valve is stuck closed
- Weak or dead battery
- The EGR passage is clogged
- Faulty EGR temperature sensor circuit
- A leak somewhere in the exhaust system
The EGR Volume Control Valve may be tested with an ohmmeter. Disconnect the electrical connector. Looking at the connector half which is attached to the EGRVCV with the latch at the 12 o'clock position you will see two rows of three terminals. The top row is numbered 1-3, right to left. The bottom row is numbered 4-6, right to left. Measure the resistance between these terminal pairs:
2 1
2 3
5 4
5 6
... all resistance values should be 20.9-23.1 ohms at 68 degrees F.
Reconnect the EGRVCV connector halves. Turn the ignition switch ON OFF repeatedly. Verify that the EGRVCV shaft moves smoothly forward backward according to the ignition switch position.
The Exhaust Gas Temperature Sensor may be tested with an ohmmeter. The specifications are ...
- at 32 degrees F, 0.68-1.11 Megohms
- at 122 degrees F, 0.09-0.12 Megohms
- at 212 degrees F, 0.017-0.024 Megohms
Last edited by matrix11229; 11-09-2007 at 11:37 AM.
11-09-2007, 06:28 PM
#6
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Join Date: Jul 2003
Posts: 686
These old threads have plenty of information on this common 4th gen problem:
http://forums.maxima.org/showthread.php?t=372440
http://forums.maxima.org/oldthread.php?t=350528
http://forums.maxima.org/oldthread.php?t=516825&page=2
http://forums.maxima.org/showthread.php?t=372440
http://forums.maxima.org/oldthread.php?t=350528
http://forums.maxima.org/oldthread.php?t=516825&page=2
Last edited by knight71; 11-09-2007 at 06:30 PM.
11-10-2007, 05:19 AM
#7
Yep, just had the same code a few weeks ago on my 99 Maxima. My egr tube was clogged. Took about 3 hours to remove the parts and clean out. Purchased both tube gaskets at Advance Auto for about $5.
11-10-2007, 12:10 PM
#9
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Location: Middleboro/Carver, Ma
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With coldish engine idling, reach way down below the TB and push up on the underside of the egr valve to manual open it, you need to stick a finger or two in the big holes on the bottom side, it's all feel, just pretend it's a girl and your going for the G spot. If your engine stalls out when you manually lift the valve open the problem is not guide tube related. If you can't push up on the valve than it is stuck and will require replacement. If it stalls something else is wrong, I can help you diagnose that also.
11-10-2007, 01:24 PM
#11
With coldish engine idling, reach way down below the TB and push up on the underside of the egr valve to manual open it, you need to stick a finger or two in the big holes on the bottom side, it's all feel, just pretend it's a girl and your going for the G spot. If your engine stalls out when you manually lift the valve open the problem is not guide tube related. If you can't push up on the valve than it is stuck and will require replacement. If it stalls something else is wrong, I can help you diagnose that also.
11-10-2007, 01:30 PM
#12
Hey I just did what you stated and I am sure I got the right thing. It like divided into 2 sections? If I put 2 fingers in there they are split apart. I pushed up on the valve and it went up and the engine idled lower. Hard to describe the sound you know but the car never did die. It sounded as if it wanted to but didnt. So now what?
I meant to turn it off. And yea the camera fell off the steering wheel also but you see what was needed. Whoops meant to click edit lol I always do that now
Last edited by Mxrider52; 11-10-2007 at 01:50 PM.
11-12-2007, 09:12 AM
#14
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Join Date: Mar 2005
Posts: 73
My guess is that it not the EGR tube although I think cleaning that has worked for a lot of people. I had the same 0302 code and when I did the manual valve test, the engine would almost stall.
Mine turned out to be that my EGR-BPT valve was bad and not allowing any vacuum signal through. It would be best to try and understand the entire EGR system before you go replacing the valves.
Here are the 3 valves in the system:
-EGR valve (directs exhaust back to the intake through the EGR tube)
-EGR-BPT valve (controls the strength of the vacuum applied to the EGR valve depending on the amount of exhaust backpressure)
-EGRC solenoid valve (an upstream "switch" that prevents the vacuum from going to the other valves depending on certain conditions like low coolant temp)
The vacuum comes from a hose on the top of the throttle body and goes to the EGRC solenoid valve that switches the vacuum on and off. It then goes to the BPT valve that controls the amount of vacuum depending on backpressure. The vacuum out of the BPT goes to the EGR valve which opens and closes controlling the amount of exhaust going back to the intake.
The easiest way to test if it's the EGRC valve it to bypass it and put the vacuum right to the BPT valve. If the diapraghm of the EGR valve doesn't lift by itself when you rev the engine then the BPT valve might be bad or there could be a clog in one of the vacuum tubes.
this is all explained fairly well in the factory service manual. I can email you that section if you don't have it.
JR
Mine turned out to be that my EGR-BPT valve was bad and not allowing any vacuum signal through. It would be best to try and understand the entire EGR system before you go replacing the valves.
Here are the 3 valves in the system:
-EGR valve (directs exhaust back to the intake through the EGR tube)
-EGR-BPT valve (controls the strength of the vacuum applied to the EGR valve depending on the amount of exhaust backpressure)
-EGRC solenoid valve (an upstream "switch" that prevents the vacuum from going to the other valves depending on certain conditions like low coolant temp)
The vacuum comes from a hose on the top of the throttle body and goes to the EGRC solenoid valve that switches the vacuum on and off. It then goes to the BPT valve that controls the amount of vacuum depending on backpressure. The vacuum out of the BPT goes to the EGR valve which opens and closes controlling the amount of exhaust going back to the intake.
The easiest way to test if it's the EGRC valve it to bypass it and put the vacuum right to the BPT valve. If the diapraghm of the EGR valve doesn't lift by itself when you rev the engine then the BPT valve might be bad or there could be a clog in one of the vacuum tubes.
this is all explained fairly well in the factory service manual. I can email you that section if you don't have it.
JR
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