SES light comes on

[quickv6]

When driving 75 MPH and undewr load the SES light comes on. The boost is around 8psi. I can drive a 70 under load with boost in the same range and no problems. I do not have a scan tool to check codes but I am sure it is boost related. I also notice that power is reduced until I pull over and cycle the key. Then all is good again. Is the boost to high causing this problem?

[patrick m.]

8psi should not set a code.
you probably have a different problem, time to check out the code. Pre-96 models will flash codes, go to "Kennedy's" web site for instructions.

[quickv6]

I posted this question 2 times by accident. The code is a 78. I have replaced the boost sensor. Same problem.