Here are the explanations for the codes you have:
P1128 Oxygen Sensing Adaptation Range 2 (cylinder 1-3) - Enrichment limit
P1130 Oxygen Sensing Adaptation Range 2 (cylinder 4-6) - Enrichment limit
These are Range 2 faults which covers the engine operating state close to idle. And Type 4 faults meaning Short to B+ / Above upper limit / Rich mixture threshold
It's not likely you'd lose O2 sensors from both banks simultaneously.
The Factory Repair Manual lists possible issues for P1128, P1130 as:
- – Air intake leaking.
– Fuel pressure too low.
– Fuel injectors contaminated (carbonized).
- Fuel supply volume too low.
But, this is not all-inclusive. A Vacuum leak past the MAF can also create a lean condition as could a faulty MAF.
Since you hear a hissing, check first for vacuum leaks, also check the 'j' tube of the AOS as these have been known to collapse and crack. This too could introduce un-measured intake air (do you have any smoke at startup?)
If the MAF
indicated too much air (I say indicated because a failing MAF can send this signal even though that's not the case), then again the DME would try to compensate and the O2 sensors would see a 'too rich' sample.
Also, you fail to mention MY. It is also possible that a clogged fuel filter could also throw this code, though probably the least likely cause.
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