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p0401 fault code on 1998 toyota rav4

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Sep 7, 2016, 11:40 AM

Post #1 of 2 (1156 views)
  post locked   p0401 fault code on 1998 toyota rav4  

My mechanic put a new evap modulator valve on my rav4 even though when I hooked a
pressure guage up to the Q nipple it read 20 when I revved the motor. I though that
meant the modulator was ok.

I told him I wanted him to replace the vsv egr solenod that the vacuum from port Q goes to.
He said he wanted to put a new egr moduator valve on anyway. He said
the modulator is usually the problem and the vsv egr solenoid valve rarely went bad.

He had cleared the 401 code by disconnecting the negative battery.
Anyway the 401 code came back pending.

Is it possible that when he cleared the set code p0401 by disconnecting the negative
battery that it cleared the code that set the SES light but did not clear the pending
code. If that is correct then maybe the pending code would not have set the code
and turned on the SES light.

I have already tested the egr valve by hooking up my manual vacuum pump and when you
pump pressure to the vacuum connection on top the motor does stumble and does
die. So I guess the egr is not stopped up by carbon and it is working.

I did note that when the RAv4 is idling the front throttle body vaccum connection
has no vacuum. The rear on does have vacuum. Am I correct about that being
correct because the front vaccum connection is in front of the butterfly and does not
get vaccum from the engine until the throttle is opened up.

I ordered a vcv this morning. I believe that is the only thing left to replace.

Hammer Time
Ultimate Carjunky / Moderator
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Sep 7, 2016, 2:18 PM

Post #2 of 2 (1148 views)
  post locked   Re: p0401 fault code on 1998 toyota rav4  

Please don't start a new thread for the same problem.

This one is locked now


We offer help in answering questions, clarifying things or giving advice but we are not a substitute for an on-site inspection by a professional.

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