i have a 2022 buick encore awd and i got the p0146b and d code. i cleared that and now i get the p0146d all the time. it leans to the evap pump. but i wonder if the trax is similar and if so has anyone had issues with this code and maybe how to resolve it? or maybe a pin out of the pump wiring so i might be able to power the pump and see if it sens back to the ecu that it is running if it runs at all. i tried the buick forum but i'm not getting any response so maybe some guys here can help out? thanks

 

There is a recall on that issue, you should be able to call your local dealer, give them your VIN, make, model and mileage to see if your vehicle qualifies for the recall, the trax are usually similar engine wise, being they are both GM, there are tests you can do yourself like a vacuum test on the pump with a hand held vacuum pump they’re pretty inexpensive, the pump should hold vacuum when not activated, as for pinning the pump, you would need the wiring diagram, a good scan tool will also have a function in the engine menu (on most, may be in another menu on others) where you can actuate the pump on and off, I’ll do some more research to see if i find anything else, hope this helps.

 

Hold on a second before you try to manually power that pump. The Encore and the Trax share the same architecture (especially if it's the 1.2L or 1.3L turbo), but "hot-wiring" components on these newer GM ECUs is risky.

First, I think you might mean code P146B (not P0146B). P146B is a generic "EVAP System Purge Pump Performance" code. It’s actually a very common failure on these cars.

Do not try to jumper 12V to the pump unless you have the exact schematic. Many of these modern EVAP pumps are not simple 12V DC motors; they can be PWM (pulse width) controlled or have feedback circuits. If you poke the wrong wire with 12V, you will back-feed voltage into the ECU and fry the driver.

The "correct" diagnostic procedure here isn't to use a multimeter or jumper wires, but to use a scanner with Bi-Directional Control (Active Tests).

1. Plug the scanner in.
   
2. Go to Active Tests > Engine > EVAP Purge Pump.
   
3. Command the pump ON from the screen.
   

If the ECU commands it on and you don't hear it hum, the pump is dead (or jammed). If it runs but you still get the code, it's likely a vacuum leak or the pressure sensor.I use an Autel MK808BT PRO for this because it’s one of the few sub-$500 tools that actually supports GM Bi-directional controls to run these pumps without needing a dealer subscription.
Check that P146B code again though—if it is that code, there might also be a GM technical bulletin (TSB) covering it, so check with the dealer before you spend money on parts.