Need some help Code P0402

I went to my regular mechanic and he pulled this code P0402 from my 2001 Pre-Runner 2.7 2wd. 150K miles. He said that it was one of three things...either the EGR modulator, EGR Valve or EGR selonoid/VSV Switch. This was just a guess as no trouble shooting was done. I systematically replaced each item above and it still pulls the same code. Yes I reset the computer each time. In addition to the parts I threw at the problem I also took apart and cleaned out the throttle body plus I sea foamed it twice. My next thought is to bite the bullet and have a dealer diagnose the problem. My thoughts are pointing towards the Cat/converter and the O2 sensors both up and downstream. My thinking is the o2 are probably overdue to be changed anyway and I am running out of parts to replace...has anyone else been down this dark road.

 

http://www.tacomaworld.com/forum/1s...weak-error-code-p0402-egr-excessive-flow.html

 

Thanks, but I already read this thread/link you referenced...the solenoid vsv switch solved the problem...I have already replaced mine and still have the CEL lit up.

 

How do the vac lines look? It only takes a small hole or blockage to screw it up. Test your lines and see if they hold a vaccuum.

 

Thanks for the tip, is there a particular line I need to remove to test for this purpose? I assume it one that is connected to the EGR. Am I looking for suction from the line and or the engine to stall out etc? Can I test it from the Modulator connections?

 

Does anyone know where the manifold Air Pressure Sensor is located on the 2.7 liter?

 

Any vac line you want to test should be disconnected at both ends, plug one end and use a vac hand pump to see if it holds a vac. 10-15inHg for a minute.
The tacoma has a Mass Airflow Sensor, not a MAP. It will be in the intake, after the air filter, with a large connector attached. It measures how much energy it takes to keep a wire at a given temp. The MAP measures intake vac pressure, and is not used.

 

thanks for the vacuum test advice. I am now focusing on the PCV as this thing looks original. Changed it tonight with a Borg Warner looks a little different but it fits. I think I change it every 30K or so from now on. Next I have the upstream fuel air sensor coming from Rock Auto. Once I change that I am hopeful it gets the CEL out of my life once and for all.

 

sooo... who is Pat Goss and what was the fix?

 

It was the ECT sensor aka coolant temperature sensor located on the back of my 2.7 liter close to the fire wall...it was a "b" to access it and you will need special socket wrench to wrangle it out. I wish I had seen this link before I replaced all the unnecessary parts. Pat Goss has his own segment each week on a show called Motorweek. Here is an excerp and link below.

Some sensors have more influence on engine performance than others. These include the coolant temperature sensor, oxygen sensor, throttle position sensor, and manifold absolute pressure sensor.
The coolant sensor is often called the master sensor because the computer uses its input to regulate many other functions, including:
Activating and deactivating the Early Fuel Evaporation (EFE) system such as the electric heating grid under carburetor or the thermactor air system.
Open/closed loop feedback control of the air/fuel mixture. The system won't go into closed loop until the engine is warm.
Start up fuel enrichment on fuel-injected engines, which the computer varies according to whether the engine is warm or cold.
Spark advance and retard. Spark advance is often limited until the engine reaches normal operating temperature.
EGR flow, which is blocked while the engine is cold to improve driveability.

http://www.goss-garage.com/node/100

 

The cel light came back on....as it turns out it appears to have been a faulty egr temp sensor. I pulled it out to replace it and the tip of the sensor had a significant build up of carbon. I pulled the fuse to reset the CEL, so far so good. I also changed the fuel filter as it had the original one installed. When I turned over the filter and a lot of black liquid came pouring out I guess it was over due for a change as it has 153K miles.

 

P0402 came back. I changed out the fuel temp sensor and it did not fix the problem. My idle is dropping below 500RPM...Really stumped here. I pull the EFI fuse to reset the CEL after 6 cold starts the CEL comes back....There must be a connection between the low idle and P0402. Perhaps the IAC needs cleaning or replacing....This will involve removing the throttle body and removing the IAC to clean it out. I am not sure I am up to this task. Does anyone have any direct experience with doing this?

 

dang, that sucks man. I have not ideas to offer but am still interested in the resolution. gdlk.

 

Okay as it turns out it was the VSV solenoid. This was a part I replaced early in the process of trying to fix the issue. The VSV Solenoid I purchased was a used part from EBAY. I didn't know they sent me a DOA part. So I continued to throw parts outside the EGR system thinking something else was causing the P0402. I did take it to three mechanics for trouble shooting one was a Toyota Master tech. None of the three mechanics could find the problem. The Toyota master tech suggested I throw the air/fuel temp sensor part at the problem.... which I did. I finally took it to a mechanic just up the street and he found the issue in one hour. They have a very good diagnostic computer on-site. Even new parts have been known to be DOA... so the lesson here is take it to a place that has a good diagnostic tech and or computer to isolate the problem.

 

In regards to my low/surging idle problem. I disassembled the snorkel just after the air filter box and mass air flow sensor and while the truck was running I sprayed 3/4 of throttle body cleaner into the TB snorkel as I worked the throttle plate to keep it from stalling. This technique seems to have alleviated the idle air control valve from sticking. I am now on the happy camper road again.

 

what is the VSV solenoid,,? where is it located..? How much to replace it..?
thanks,
shawn

 

On my Tacoma it has a 2.7 liter its on the drivers side of the engine under the intake manifold. Its a dealer item only they are around $100.00.