Toyota Repair: 2002 Camry V6 -- P1155, P1135, air fuel ratio, voltage waveforms

Question
Dear Sir,

I am help my friend to solve a check engine light problem for smog purposes.  It currently reads P1135, P1155.  We swapped a working MAF and the vaccum switch next to it but the same codes come back.  In the past, a shop had changed both Bank-1 & Bank-2 O2 sensors also the same codes came back.  Any suggestions?  Should we buy a new OE Bank-1 O2 sensor and try again?  This problem occurred at 15,000-20,000 miles (in 2003) when he attempted to install the TRD supercharger.  The supercharger did not crank, he put back everything and the 2 engine codes were on since then.  Would you suggest that the ECU is fried?


Looking forward to your response ASAP,

Chuck


Answer
The ECU is the last thing to suspect, the first thing that should be done is to connect an obd scantool to see what the O2 sensors are doing, their operation can be observed by looking at the voltage waveforms of the sensors, on a 2002 the number one sensors are air/fuel ratio sensors not O2  sensors, these will show a voltage that will vary a very small amount but should stay around 3.25 volts, hope this helps.