2010 Toyota Camry 2.5Lp0136replaced the O2 sensor and within 50 miles the code came back

Question

2010 Toyota Camry 2.5L
I replaced the downstream O2 sensor for a P0136 code.
Within 50 miles the code returned.

Any other common causes for this code??

Answer 1

Other causes besides oxygen sensor or wiring issue is 

- Inappropriate fuel pressure
- Faulty fuel injectors
- Intake air leaks 
- Exhaust gas leaks