What does the code 172 mean for a 2005 GMC Canyon?

Location

https://www.google.com/search?q=2006+gmc+canyon+canister+purge+valve+location

The Codes

P0455 GMC Code - Evaporative Emission Control System ...

https://www.engine-codes.com > p0455_gmc
P0455 GMC Code - Evaporative Emission Control System Leak Detected Gross Leak · Possible Causes · How To Fix · Tech Notes ? · Cost to Diagnose · Meaning.

P0442 GMC Code Evaporative Emission Control System Leak ...

https://www.autocodes.com > p0442_gmc
Aug 17, 2017 - The P0442 code means that the control module has detected a small leak in the Evaporative Emission (EVAP). Loose fuel tank filler cap is the ...

Code 172 means the O2 sensor is telling the computer the fuel mixture is too rich.
The computer adjusts fuel mixture thru the injectors based on data from the O2 sensor among other things.
The problem could be the O2 sensor or something else like a faulty injector or air restriction.

Hi there:

Basically this means that the the car's computer has detected that not all of the engine's cylinders are firing properly.


A P0300 diagnostic code indicates a random or multiple misfire. If the last digit is a number other than zero, it corresponds to the cylinder number that is misfiring. A P0302 code, for example, would tell you cylinder number two is misfiring. Unfortunately, a P0300 doesn't tell you specifically which cylinder(s) is/are mis-firing, nor why.

Symptoms may include:
the engine may be harder to start
the engine may stumble / stumble, and/or hesitate
other symptoms may also be present

A code P0300 may mean that one or more of the following has happened:
Faulty spark plugs or wires
Faulty coil (pack)
Faulty oxygen sensor(s)
Faulty fuel injector(s)
Burned exhaust valve
Faulty catalytic converter(s)
Stuck/blocked EGR valve / passages
Faulty camshaft position sensor
Defective computer


Possible Solutions: If there are no symptoms, the simplest thing to do is to reset the code and see if it comes back.


If there are symptoms such as the engine is stumbling or hesitating, check all wiring and connectors that lead to the cylinders (i.e. spark plugs). Depending on how long the ignition components have been in the car, it may be a good idea to replace them as part of your regular maintenance schedule. I would suggest spark plugs, spark plug wires, distributor cap, and rotor (if applicable). Otherwise, check the coils (a.k.a. coil packs). In some cases, the catalytic converter has gone bad. If you smell rotten eggs in the exhaust, your cat converter needs to be replaced. I've also heard in other cases the problems were faulty fuel injectors.


Random misfires that jump around from one cylinder to another (read: P030x codes) also will set a P0300 code. The underlying cause is often a lean fuel condition, which may be due to a vacuum leak in the intake manifold or unmetered air getting past the airflow sensor, or an EGR valve that is stuck open.


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That's a misfire code, does the vehicle feel like its running rough? If not it may just be a bad batch of fuel or even time for a tune up depending on mileage.

You can to the Salvage Yard for a new computer, but your going to have to get it reprogram to your ignition keys, so the Passlock will start the engine. Before you go through all of that. recheck every thing, it could be your crank sensor or your ICM faulty causing your engine to shut down. Keep me posted and let me know what DTC codes you have. Note: a faulty fuel pump or dirty fuel filter will not set a DTC code. You may have a dirty fuel filter or faulty fuel pump or faulty fuel pump wire harness or fuel pump relay.

From http://www.obd-codes.com/trouble_codes/
The P0300 is a misfire and P0506 indicates low RPM at idle.

A misfire can be caused by poor ignition (spark plug, plug wire, coil, ignition module/engine control module).
OR
Poor air/fuel (air filter, fuel injector, fuel pressure, fuel filter, fuel pump, bad gas, or engine control module).

Check your maintenance requirements and see if any of these items are due for replacement first.

Most likely you have a faulty ignition coil, it is possible that you have a bad fuel injector

As requested

it should be mounted on the charcoal canister near the fuel tank

you might have the brake shoes adjusted out too much, back them off a little bit and far as the sensor goes, its located on the fuel rail where the injectors are.