I have been getting a overboost code. I am about to test the wastgates and the lines that go to them. My question is the line comming of the boost frequency valve to the wastgates are they working on boost or vacum? Also which line goes to the wastgates? If they are working on vacum what tool can be used to check with? I have a shop with a compressor. Thanks...Robert

 

The wastegates are pressure activated. When you get the P0234 code it could be frequency valve, a leaking hose to the wastegates, wastegates not adjusted correctly and evenly... or in my case, it was a boost leak when a clip on my boost hose came loose on one side

 

so at the line going to the wastgates from the boost frequency valve i use vacum or + pressure to test for leaks?

 

When they are operated they are pressurized. So to test the lines, pressurize them- or to operate the wastegates, again pressure. ~15psi MAX.

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Boost Pressure Characteristic, Upper Value Exceeded - Above Limit

Possible fault cause
♦ Leakage at pressure hoses from frequency valve to the bypass
flaps
♦ Frequency valve faulty
♦ Vacuum modulators for bypass flaps leaking
♦ Bypass flaps incorrectly adjusted

 

Thanks guys.....Wross what is a vacum modulator for bypass flaps...and is term flaps the wastgates?

 

Since I have the same problem now, did you ever figure it out? Was there other codes along with this one?