Volvo Repair: Volvo trouble code, volvo s80 t6, mass air flow

Question
My 2000 Volvo S80 T6 has recently had a string of problems. It started with a misfire in #3 cylinder, I fixed that by changing #3 coil pack. Then onto random misfires, changed the plugs and fixed that problem. The car still ran poorly, I had all the codes cleared, ran it, then had it rechecked. The current OBD II code that was brought up is P1238. I cannot find what the code signifies, due to the fact of it being a manufacturers code. Could you please point me in the correct direction. I am almost at my witts end. Thank You

Answer
That code converts to volvo code ECM-6806 and the code description as described in the volvo service manual:


284: ECM-6806 Turbocharger (TC) control system flow fault. Flow too high/low. Permanent/Intermittent fault, B6284T           

Diagnostic trouble code (DTC) information

Condition
If engine speed (RPM) is above 3500 rpm and the engine is operating at a high load, the control signal to the turbocharger (TC) control valve is at maximum and the boost pressure (from boost pressure sensor) is lower than a designated value (approximately 20 kPa (2.90 psi) under normal boost pressure - signal too low).
If the air mass (from mass air flow (MAF) sensor) is higher than a desired value (signal too high) it is interpreted as a fault and diagnostic trouble code (DTC) ECM-6806 is stored.  

Substitute value
reduced boost pressure

Possible source
Signal too high:
-air leakage after turbocharger (TC)
Signal too low:
-hoses between turbocharger (TC) and turbocharger (TC) control valve respectively turbocharger (TC) control valve and pressure servo are loose or are blocked/damaged
-faulty turbocharger (TC) control valve
-faulty boost pressure control (BPC) valve pressure servo
-sticking boost pressure control (BPC) valve  



I would say that considering you just replaced coils and all the tubes were off on top of the engine, one of them may be loose, leaking or damaged.  Good luck fault-tracing.

James