P1128 Diagnostic Trouble Code

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dtschroe - 06 Oct 2005 22:37 GMT

I recently purchased a 1999 996 C4. Shortly there after the check
engine light came on. I bought a OBD-II device to read the DTC from
the ECU. The trouble code is "P1128." The OBD-II device displays a
message something like: "Manufacturing air fuel mixture ..." Does
anyone have a suggestion about what would cause this and how to
resolve?

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The Dead Senator - 07 Oct 2005 02:53 GMT

> I recently purchased a 1999 996 C4. Shortly there after the check
> engine light came on. I bought a OBD-II device to read the DTC from
> the ECU. The trouble code is "P1128." The OBD-II device displays a
> message something like: "Manufacturing air fuel mixture ..." Does
> anyone have a suggestion about what would cause this and how to
> resolve?

http://www.renntech.org/forums/lofiversion/index.php/t2555.html

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Regal53 - 12 Oct 2005 02:29 GMT

As per Porsche's own OBD manual:
P1128 Oxygen sensing Adaptation Area 2 (cylinders 1-3)--Rich Threshold.
Fault conditions:Fuel/Air mixture is so lean that sensing has reached its
rich threshold.
Fault area:Intake air system leaking; fuel pressure too low; volume supply
of fuel pump too low; fuel injectors fouled. ( I always found leaking air)
Air leaks ahead of the oxygen sensors can lead to a fault in adaptation:
check exhaust system for leaks too.
P1130 is the same fault for cylinders 4-6. I am no longer associated with
porsche, so glad to help.

>I recently purchased a 1999 996 C4. Shortly there after the check
> engine light came on. I bought a OBD-II device to read the DTC from
> the ECU. The trouble code is "P1128." The OBD-II device displays a
> message something like: "Manufacturing air fuel mixture ..." Does
> anyone have a suggestion about what would cause this and how to
> resolve?

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