CEL Codes

I’m getting the following codes, and I’m not sure what to start with checking. Last summer my fuel pump went out, and I had that replaced along with a new MAF sensor because I kept getting P0101. fast forward to now, truck has been great until about the last 3 weeks.

Truck will randomly throw P0101 and C1201 together, never separately. Truck runs fine even with the codes but no clue. I’ll reset the code and even pull the MAF to spray cleaner, and it may be fine for a few hours or days. Today, I got the system banks being too rich also, which was the first time I’ve had it.

My truck is an 08, 4.7L, and has the gen 1 Hewitt Bypass kit on it for probably 3.5 years. My local dealer initially thought before it was the bypass kit, but my understanding of that is, it’s keeping the AIP system from turning on, and that’s it.

Any thoughts??

 

The C1201 is a generic code for engine control malfunction.

I would be looking closer at the MAF. It having an issue could trigger all the other codes with it.

Almost seems like when you unplug it and clean it, it resets for a few hours.

I might start looking at the wiring connector to the MAF and signals on the wires. Wonder if something stupid like an intermittent voltage or signal drop is making the ECU think the MAF is not functioning.

When I get a minute I will look in the repair manual to see if Toyota has a process for testing MAF wiring ect.