From TSB,
P0133 - HO2S Sensor Circuit Slow Response (HO2S-11) The HO2S monitor checks the HO2S sensor frequency and amplitude. If during testing, the frequency and amplitude were to fall below a calibrated limit, the code will set.
Electrical:
�· Shorted/open wiring
�· PCM
Induction System:
�· MAF sensor (On 4-cylinder engines, if P0133 is present, this could be caused by a MAF issue - on 6- and 8-cylinder engines, this could only be a MAF issue if P0133 and P0153 are both present)
�· Inlet air leaks (unmetered air)
Fuel Concerns:
�· Poor fuel quality
Base Engine:
�· Exhaust leaks (upstream or near HO2S)
HO2S Concerns:
�· Contaminated HO2S sensor (contamination from the use of silicone-based cleaners and sealants, leaded fuel, excessive oil consumption, etc.)
�· Deteriorating HO2S sensor
