Toyota Camry: Code P401 on '98 Camry

The "check engine" light on my '98 Camry 4 cylinder is lit.

The OBD show a code P401, indicating insufficient EGR flow. I've pulled and
check the EGR valve and it seems to work fine (no sticking or clogging),
I've cleaned the EGR tube from the manifold to the valve (by running a wire
down it).

I tested the MAP sensor according to the Haynes manual. The voltage differed
from what they indicated, so I changed it at a cost of over $300. The
voltages are exactly the same and the MIL still lights, even after clearing
the code.

I've by-passed the VSV by connect the vacuum hoses directly.

I THINK I by-passed the vacuum modulator (I connected the vacuum hoses
directly from the manifold to the EGR valve).

I've tried everything I could think of, short of just changing part by part
hoping to hit upon the right one. I don't know what, if any, sensor actually
measures the EGR flow and if it could be bad and giving a false problem
reading.

Nothing I've done gets the light to go out. I don't notice any decrease in
engine performance of gas mileage. In New Jersey, where I live, a car won't
pass inspection with the MIL lit or any OBD codes active.

Any suggestions would be greatly appreciated. Thanks.

If you are willing to invest about $300 for a scan tool then consider
AutoXray 4000 which is OBD II and works for your car.

I had P0401 on my car and it was the EGR valve, MIL was coming on only when
I add Injection cleaning to the fuel. No air should flow when valve is
closed, possibly the EGR valve is damaged so it does not fully open or there
is a leakage in a rubber pipe at throttle or EGR that drops vacuumed
pressure on the EGR valve so it does not fully open.

Read about it at http://www.autoshop101.com/


"Tom C" <com> wrote in message
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