P0401 comes ,so I cleaned the egr valve and the svs, but after a not too lon drive the chek engine came back. I put the scanner and it shwos the same code again. What could be happenig whit tha egr or svs., or maight be something else?

Hi Joe

Like all solenoid valves, you can clean them with throttle body cleaner and then test the solenoid electronically with a 12 volt supply.

P0401 Exhaust EGR Flow Insufficient

Toyota Nation Forum https://www.toyotanation.com > threads > p0401-exha...
May 1, 2014 - The sensor is how the ECM determines there's insufficient EGR flow. It's on the intake-side of the system and if not enough exhaust-gases flow ...

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P0401 : EGR Flow Insufficient on 1996 Toyota Corolla

OBD-Codes.com https://www.obd-codes.com > forums > viewtopic
Jan 20, 2007 - on EGR codes, we recommend replacing the EGR, vacuum modulator and VSV (if equipped) and cleaning out the carbon buildup to the intake from the ...
If that finds nothing wrong, remove the EGR valve and bypass tube and check them for cleanliness and blockages. If they are blocked, follow your maintenance manual's instructions for cleaning them out so you do not damage the valve, then replace them and reset the ECM.

Insufficient EGR Flow - P0401 Code - Toyota

if you manually push up on the EGR valve and the engine doesn't stall and the passages are all cleaned out then the problem is the EGR valve.

Could be a EGR vacuum issue or temp sensor issue

Common Problems That Trigger the P0401 Code

• Restriction in the EGR passages, usually caused by carbon buildup
• Lack of a proper vacuum signal to the EGR Valve from EGR Vacuum Solenoid
  
• EGR Vacuum Modulator is defective
• EGR Temperature Sensor is defective
• EGR Valve is defective

This is from:
http://repairpal.com/OBD-II-Code-P0401-Ford

Hi,

P0401 means insuffient EGR flow:

EGR stands for Exhaust Gas Recirculation, which basically sends some of the exhaust back into the engine cylinder again. Your error means that there isn't enough of the exhaust gas making it back to the intake manifold.
The first thing I'd check is the tubes coming off of the EGR valve to make sure they aren't clogged or broken. Then I'd check the EGR valve itself and the throttle body. The problem is usually:
1.) Carbon buildup causing a clogging.
2.) Broken hoses.
3.) Broken Valve.

Best regards.

P0401: Isufficient Flow Detected in EGR system.
-clean the EGR port with the carburetor cleaner.
-clean the EGR passage inside the EGR valve with the caburetor cleaner.
Reset the light, if the light still coming back, then replace the EGR valve.

check the metal line that comes off the exhaust and make sure it isnt plugged with carbon. also remove the egr and check the port and see it's clogged as well

your egr valve may be bad or you mite be just clogged. take it off and see if there is any deris in egr vavle or the hole on to mounting service if so clean out. if not replace the egr valve.

Have a little read of this link, it may help you.

http://www.obd-codes.com/p0401

Code on diagnostics p0401:

What is going on?
Exhaust Gas recirculation low flow detected means that: there is vacuum problem in the EGR system - between the combustion chamber, EGR valve (mechanical - blown up diaphragm or clogged airlets/hoses) , EGR Modulator Valve (mechanical - blown up diaphragm, dirty EG/air filter or clogged airlets/hoses) and Vacuum Switching Valve ((mechanical - blown up diaphragm or clogged airlets/hoses OR electrical - VSV not properly synchronizing with the ECM, for instance).

Effects?
This causes the combustion chamber temperature to increase and produce Oxides of Nitrate (NOx) that is out of an acceptable emission range. This triggers the Malfunction Light (check engine light) to stay on (after a couple of driving cycles)!
Solution: Focus on EGR airways (hoses...) and organs (EGR valve, EGR Modulator, VSV), clean, check or replace the defected one. VSV seems to be criticale as it plays electrical & mechanical function. Once the repair is done, Clear the P0401 code using an OBII scanner.

Jason,
-after you change the part you have to reset/clear the code

-this can be done by either:
(1) using the OBD2 code reader that Autozone used OR since option 2 (below) is very quick
(2) disconnecting the battery for about 30 seconds (this will delete all codes/radio presets/etc) but it will also clear the 'check engine' code
-this is what I do AFTER i write down my radio station presets :)

-hopefully the new EGR valve resolves your issue after you CLEAR the code
...but that code just means a an insufficient amount of Exhaust Gas recirculation (pressure difference) used to keep the emissions in check
-if it comes back, then there are a few other fixes to try also

-let me know if you need further assistance
-please remember to rate me `fix-ya`if it works
thanks