Purge Valve replacement issue

[nweb992000]

I had the purge valve replaced on my 2017 ST after it would not start after filling the tank. The code was P1450.
Now, after the replacement, when I hit the brakes, the wrench icon lights and the message
Hit Start Assist
Not Available
pops up on the screen and another P1450 is logged.
I will take it back to the shop on Monday and see what's what. Just wondering if anyone has run into this, being the Purge Valve is a common trouble point. Why the brakes? It seems like an unrelated system.

 

[Handy Andy]

This sounds more like a vacuum drop issue, which would affect the purge valve because there is loss of vacuum and the line itself, it's hose can be plugged, kinked or worse - letting air seep past the check valve and back into the canister / fuel tank - changing the fuel tanks pressure - which can cause that code to re-appear.

So look for and recheck all your vacuum lines - including the ones from the air intake snorkel to the engine - which will share a similar position on the intake.

Now there are two types of ST - one with the turbo and the ST-line type which is normally aspirated (N/A - non-turbo - uses throttle plate and normal air pressure) - so to have this code set usually indicates damage to a line that got whacked by road debris - which may mean Turbo and it's mechanical parts are possibly compromised - which again, changes flow rates and pressure changes in the fuel tank - setting this code.

The Hill Assist is a good strong clue that this is vacuum related - not necessarily a bad turbo, but the tubing in and around the turbo (if it's the one that has it) may be compromised and the built in safeguards are still in place but something in the EVAP line - relating to vacuum - is affected.

How does Hill Assist tie into this? By Vacuum used in the Brake Booster - when the vacuum drops - the booster can't or may not, be able able to provide enough braking - so it turns off hill assist so you are aware of the brakes having less reserve due to the vacuum leak in the system that Hill assist will need to apply (keep up) the pressure in the brake line.

You may also feel a change in the brake pedal when you start the car after it sits overnight. If it's lost all vacuum in the booster - that check valve - the pedal will feel stiff and firm - but start the car, and if you keep pressure on it, the pedal will recover some of it's spongy feel after the engine is started and the booster retrieves vacuum to restore operation. Do not be surprised if the battery and the EPAS (steering control) is also affected for all of this uses electrical power to operate the valves so if the alternator or the battery or both are weak and have long seen better days - time to rethink and replace - before it leaves you stranded.

If that is occurring - several other things will need to be checked - especially under the car, the undercarriage - because there may be some damage and road rash that is affecting the lines under the car from the incident.

 

[nweb992000]

That was a good reply, thank you.
The air leak idea makes sense to me,
but the car is not a turbo and is in excellent condition, kept garaged, and never abused or had any hard driving. So, with only 43K miles on it I'm a little surprised I'm having the issue, but it has been on the road for 5 years. It goes back to the shop tomorrow, I'll assume finding a leak is typical problem for them. Thanks again for the heads up.

 

[scotman]

Minute evaporative emission leaks are most quickly and reliably resolved if you connect a smoke machine leak detection device to evap system. Even the tiniest little leak reveals itself. It’s unfortunate that the damn thing is so expensive. It’s expensive enough that I just take the car to the dealership for diagnostic and repair because it’s still under warranty in terms of the emission useful life.

 

[Handy Andy]

To help further, this could even be as simple as a leak in the fuel nozzle they use for the "no cap".

It is a two piece unit and a seal is sandwiched between the two - it can even generate a vacuum leak so the system thinks something is seriously wrong (at least enough to tell you some other conveniences like Hill Assist) and disable some secondary functions you normally don't deal with.

​

In order to even be mounted it uses a grommet - you can figure that in some instances that grommet will develop a leak and there goes the seal - setting a check engine light and some silly code you can't track down because it doesn't know what to do.