Kyle09TC

P0238 Overboost. Need help.

33 posts in this topic

I posted the picture of the Boost sensor as I understood it wasn't identified clearly.

It is intended to show the electronic part that detects and sends the fault code.

The actuator does not have any means of detecting over or under boost. The diaphram and internal spring in the actuator responds to the air pressure from the turbine. If the hose that controls the actuator is cracked air pressure escaping will be insufficient boost. If it is plugged by oil leaking from the turbo it will also have under boost.

The only way to control the overboost is to back off the travel distance of the actuator rod by moving the adjustment nuts, therefore the opening action of the wastegate valve is set sooner

I hope this clears up the understanding.

 

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You are again muddling the water GRP151. 

Cracked and leaking actuator hose will cause overboost and possibly limp mode. Oil in actuator hose causes no problem at all. 

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7 hours ago, tolsen said:

You are again muddling the water GRP151. 

Cracked and leaking actuator hose will cause overboost and possibly limp mode. Oil in actuator hose causes no problem at all. 

 

If crack hose gives overboost  what is actually happening?

Is it not enough pressure to retrack the actuator or to extend it?

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4 hours ago, Ritchie said:

 

If crack hose gives overboost  what is actually happening?

Is it not enough pressure to retrack the actuator or to extend it?

You don’t need to be particularly smart to figure that out. 

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If the hose to the actuator is cracked, or if the diaphragm in the actuator itself is torn, the boost leaks out and can't build enough pressure to compress the spring in the actuator. So the rod doesn't extend and the wastegate doesn't open, boost keeps climbing, and you get an overboost code and limp mode.

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Hi there,

I'm still having the P0238 issue. I haven't had the chance to pull the rear panels off to adjust the waste gate rod. Maybe driving in limp mode will get me better mileage I usually push it to perform. Strange why it  would clear itself after a few km's and restarts from sitting a while?.

The engine light goes off and it's drivable again with no problems.

I'm not sure how many km it takes to return the engine light and limp problem.

I wonder why it would clear itself if it was out of adjustment or cracked hose.

Shouldn't the engine light and limp mode continue?:confused:

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My car had this error occur after driving about 2 km and going up the same hill while going to work every day.

 

Removed the rear panels and freed the wastegate.

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Ritchie

Turbocharger boost changes with engine load from a slight vacuum at idle to max boost going uphill with your foot into it.   Unlike a supercharger where the boost is directly linked to engine speed.  So if you drove with light throttle all day long you probably wouldn’t set the code.  

 

Nigel

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