Engine suffocating

Check your exhaust. Peterbilt had what appeared looking inside like a DPF. No sensors, just a long muffler looking filter underneath.

Found several completely plugged.


You can normally judge flow by what's coming out of the stacks.

 

Cat doesn't have EGR valve, unless I'm mistaken

 

You are correct.

Last years of CAT had something similar.

Their attempt was called Clean Gas Induction.

It took gases after the DPF and induced them back to the intake in effort to reduce NOX.

In the end it was not enough.

 

Since you’ve never said what engine? Cat, Cummins?? I know you said twin turbo so we’re all assuming you have a Cat Accert with the MXS prefix serial number since you said its an 06. If its a Cat your mechanic is wrong as cats never had the EGR system.

 

Can you take a pic under your truck at the exhaust pipe going forward? I'm telling ya, had 3 or 4 with same symptoms. All Acert Cats, and all roughly that year. If there is a long cylinder under there about 16" wide by 6' long, it's a filter.