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I just bought a 2016 ford focus st. I am already having issues with it. It seems that my ECU can’t match the amount of boost i’m pushing. Very weird noise when I hit boost and my BOV isn’t going off correctly. The car when you let off the gas throws you forward kind of. I am running very rich and i don’t know what to do. The engine code was something about “Turbo boost sensor” “Circuit A” I already replaced both MAP sensors and all the plugs and coils. Im not sure what else i can do and i don’t want to take it to a dealership, if anyone can help please help.
 

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Any mods or anything done to the car?
 

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If the car is not tuned, it might possibly be having a hard time adjusting with the aftermarket downpipe. You may want to try swapping back to the factory cat first. Regarding the BOV, I had issues with a Turbosmart one because the spring wasn't adjusted and the rubber o ring in it fell out of place. Check those two parts out first.
 

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2017 Kona Blue ST1
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What was the last thing you (or someone else) did to the vehicle?

What was the exact DTC?
 

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2017 Kona Blue ST1
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Well, strange noise under boost could be either a boost or exhaust leak.

The DTC P0238 Turbocharger Boost Sensor A Circuit High means that the PCM sees higher than reference voltage. The sensor in question houses two separate sensors. The CACT (charge air cooler sensor) measures the air temperature post intercooler and the TCBP (turbocharger boost pressure) measures the amount of pressure after the intercooler but before the throttle body.

The sensor has 4 wires. Pin1 is the SIGRTN (ground), Pin 2 is the CACT return signal to the PCM, Pin 3 is the VREF (5 VDC +), Pin 4 is the TCBP return signal to the PCM and is the offending wire.

The "high" portion on the DTC means that more than the expected voltage is being sent to the PCM. A quick test would be to disconnect the sensor and see if then code changes to "open" versus "high". *note it is important to remember that you will also see a code for the CACT because of the disconnected plug.

382186

If the code remains "high" after the sensor is disconnected you could potentially have an issue with the PCM.

You said that:
The person who owned it before me i believe was running a tune but i don’t have that access port but i ordered one that might be the issue but i’m not sure
Did you mean that he reverted the vehicle back to stock configuration and unmarried his AP from it? Or that the tune is currently installed and he kept the AP? Sorry just seeking clarification on that one.

You need to check the wiring on the vehicle for damage. As strange as it sounds double check the bank 1 O2 sensor wiring as I have seen the wiring become damaged on aftermarket down pipes and cause ass sorts of strange issues with the PCM.

Stay Safe

J
 
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