My '99 RAV4, manual trans., 64k miles, has had the check engine light going on and off periodically for 6 months.
Operating manual says could be gas cap not on tight. Since the light was coming on coincidentally when I filled up the gas tank, I tried replacing the gas cap. No effect, light still comes on and off approximately every 100 miles or so.
Had codes read at dealer and local autoparts store. Both said EGR system fault. EGR is three pieces: EGR valve, vacum module, and vacum switch. I replaced the EGR valve and the vacum module since they were easy to get at. No change, light still comes on and goes off periodically. I want to replace the vacum switch, but can not figure out how to get at it. It is mounted to the block under the air intake manifold in between the engine and the fire wall. You can not see it, nor can you get at it from on top or underneather the vehicle. Do I have to remove the throttle body, intake manifold, etc. to get at and replace the vacum switch?
I don't remember the actual code #, they were read some time ago. I will go by the local autoparts store this week and have them re-read. If I remember right, the code related to EGR low flow rate. But I will have it re-read and post the code by Thrusday.
does your egr have a sensor? like a thermistor or a potentiometer? sorry I'm not familiar with Rav4's but am familiar with the system you described. its a backpressure egr system with a transducer, vsv, and the egr valve. thats the one with a hose from the egr tube going underneath the vac. modulator, correct? also, did you clean the passages where you bolted up the egr valve when you replaced it?
No, I have not resolved the problem. I have replaced the EGR valve and the vacum module, and cleaned out the pipe connecting the exhaust to the GR valve. I have not been able to figure out how to get at the vacum switch which is located on the block between the engine and firewall, above the transmission, and below the intake manifold. I think I may be able to get at it if I remove the battery mount which is located on the passenger side against the firewall. It looks like I might be able to gain enough clearance to get at the vacum switch. In the mean time, the engine light continues to go on and off intermitently on a fairly regular basis. The vehicle runs fine, and gets the same mileage as it did before the light started coming on and off. So I haven't tried to remove the battery mount yet, or worried about it in a while.
GRMarshall, thanks for the reply. I haven't started replacing parts just yet. I am trying to locate the VSV which I think is on the rear of the block under the exhaust manifold. If that is it I think I can get to it from underneath. I want to get the part numbers before I start replacing stuff though. Like yours, it does not seem to be affecting the engine operation, although recently I've had two episodes where it has not wanted to idle when it is first started cold - don't know if the two symptoms are related. Again, thanks for the reply.
I was able to get the EGR valve from Auto Zone, who also read the P code for me. The vacum module and vacum switchs are dealer items. Each of the 3 parts was about $75 a piece. The dealer and a repair shop told me that the rough idle at start, and staling when coming to a stop are both symptoms of the EGR system not functioning properly. I have experienced the rouch idle/stalling on startup in cold weather also, but it was minor and has not happened more than a couple times over the past year. I have not experienced stalling when coming to a stop (5 speed manual). The dealer also told me that when they diagnos the EGR, they automatically replace all 3 components instead of trying to fault isolate the culprit. Hence the $400 price tag for the service if you have them do it. BTW, with the 4WD, I can not get at the vacum switch from underneath on my vehicle. The transmission/transfer case blocks access.
My 1996 Rav4 also came down with P401 code . Resetting it once got rid of it for about a week, but it is now back. I took out and tested/cleaned the EGR valve. It appears to be working just fine (opens when vacuum is applied to it).
All the other lines also seem to be clear. So the fault is probably in the vacuum module or the vacuum switch.
My local AutoZone wanted $160 for the EGR valve, which is why I decided to first give cleaning/testing a try. And I am glad I did. Or it would have been waste of $160.
To answer OEMonkey’s question, Rav4 does not appear to have an EGT thermocouple to measure EGR’s efficiency. They must be doing it through the vacuum (aka MAP) sensor or so some other OBD2 monitoring trick.
So, I am now driving on freshly cleaned/EGR valve. Since it wasn’t clogged up in the first place, I doubt that it has fixed the problem. And now, my local AutoZone is telling me that can not legally reset the OBD2 (something they had no problem with doing a week earlier).
Have anyone of you guys been successful at correcting this problem?
I have not tried anything in a while. I replaced both the EGR and the vacum module. The EGR was $75 at Autozone, BTW the EGR tested fine after I took it out also! The vacum module was another $75, dealer only. I also cleaned all the lines, as well as the tube going to the exhaust. The only thing left is to replace the vacum switch, which is another $75 dealer only. The reason I have not tried replacing it is that I can not figure out how to get at it. Talking to the dealer they said they automatically replace the EGR, vacum module and vacum swith when repairing this problem. They do not bother spending the time to trace which of the 3 is the culprit. They said it is not worth the time and money to fault isolate to the problem. I'm convinced my issue is the vacum switch. Maybe this summer I will tackle it agin. In the meantime, the vehicle runs fine, gets the same mileage and has the same around town and highway performance as before. The light comes on and goes off about every 80-120 miles pretty regularly. You can reset the cade by disconnecting the battery for a while. I've done it several times before. Also, my Autozone has cleared the codes a couple times also. Its been going on so long now, I don't bohter anymore. Good luck.
I replaced all three pieces to the EGR system for about $200 total getting Toyota OEM parts online from west coast dealer and fixed the problem. I was careful to get the actual Toyota part numbers off the parts on the RAV4 to both locate the parts and be sure what I was ordering. Very easy to install, even the VSV which was on the rear of the engine block. Mine is not 4WD though. Installing the parts and removing the EGR fuse for a minute or so to reset the code corrected the problem thus far.
This one stomped me with all the vsv valves I have
replaced in the pass. It did show a little high on
resistance but the vacuum that was coming out is the same
as the new one. I did install a new vsv valve and the
moniters did run and no more ck engine lights.
_____________________ ORIGINAL MESSAGE _____________________
This car has the egr PO401 in it. I ck the egr with hand
held vaccum pump and it killed the engine. Ck for vacuum at
the egr valve and there wasn't any, ck and replaced
transducer. Now I have 20in of vaccum at egr valve, and the
egr valve is opening. I cleared the codes, test drove and
it sets a pending code quick. I went ahead and remove the
valve and all passages are open. You give it part throttle
and the valve opens, put in gear and load the engine and it
opens. You can see the map and o2 switch when you pull the
valve open a little. This is the first time I haven't been
able to fix a PO401 code on any car. I have ck for
bulletins in alldata, but nothing on egr valve. Its
something I am over looking and maybe you guys have run
across this before.
I have never fixed my car before but I am goign to try to clean my EGR valve. The manual I have says I have to remove the trottle body before I clean out the valve. Is that necessary? From the book, the valve looks pretty accessible to me. Also, must I buy a new gasket before I attempt to clean out my valve?
Please help me out and if you have step by step instructions, it will be even better!
The EGR comes out easily with just a couple bolts.
The valve operation is pretty simple. You don't need a manual, just a can of carb cleaner and srpay, spray, spray. To test, if you apply a small amount of vacum to the input tube (like sucking on it ), the valve should move easily.
You may not have to replace the gasket, mine was metal, but it is always a good idea to do so.
While you have the EGR valve off, use more carb cleaner and some sort of large pipe cleaner to clean out the downtube connecting the EGR valve to the exhaust.
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1999 RAV4 EGR Vacum Switch
I have not resolved the problem. I have replaced the EGR valve and the vacum module, and cleaned out the pipe connecting the exhaust to the GR valve. I have not been able to figure out how to get at the vacum switch which is located on the block between the engine and firewall, above the transmission, and below the intake manifold. I think I may be able to get at it if I remove the battery mount which is located on the passenger side against the firewall. It looks like I might be able to gain enough clearance to get at the vacum switch. In the mean time, the engine light continues to go on and off intermitently on a fairly regular basis. The vehicle runs fine, and gets the same mileage as it did before the light started coming on and off. So I haven't tried to remove the battery mount yet, or worried about it in a while.
. Resetting it once got rid of it for about a week, but it is now back. I took out and tested/cleaned the EGR valve. It appears to be working just fine (opens when vacuum is applied to it).
The EGR comes out easily with just a couple bolts.
), the valve should move easily.
Linear Mode
