P1400 DPFE (Differential Pressure Feedback EGR) circuit low input
This normally due to a faulty dpfe sensor and is located above the left exhaust manifold and egr valve tube. The dpfe sensor runs under $50 and takes about 15-20 minutes to replace:
P1780 Trans control switch (O/D cancel) out of self test range
This code normally comes on because the test procedure with scanner was not done correctly.
When doing the key on engine on test, you have to press brake pedal,turn steering wheel 1/4 turn, and press OD button on then off. Failure to do this will set this code.
I would have this code reset, then see if it returns. If it does and the test is done correctly, then the o/d switch in shifter is bad
As far as the leak, it could from a bad seal tailshaft housing, or even cracked case. The only way to find out is to clean it off, run it for a day or two and get it up in the air for a thorough inspection
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