P1128

[ericsanchezm]

Hello,
I have a 911 996/1999.

I have the error code P1128.
Bank 1-sensor 1- Maximum sensor voltage-fail.
Bank 2 sensed 1 - Maximum sensor voltage fail.

Can you help me?

Is the oxygen sensor?
Is the MAF sensor?

Thanks.

[JFP in PA]

P1128 is actually the code for an overly lean O2 sensor signal on bank #1, usually a sign of a vacuum leak effecting that bank or poor fuel delivery in one or more cylinders on that bank.

[ericsanchezm]

How can I fix it?

[JFP in PA]

Originally Posted by ericsanchezm

How can I fix it?

First, using a Porsche specific scan tool, check the air/fuel ratio output on bank 1, that would confirm the code. Then pull and read the plugs on that bank to see if only one or more cylinders are running lean. Another pathway is to use a non contact pyrometer and check the individual exhaust header runner temperatures to see if one is hotter than the others. If only one cylinder, check the injector pulse width on that injector to see if it is functioning properly. If all cylinders are lean, smoke test that bank for vacuum leaks.

[ericsanchezm]

Thank you.