P1238 VOLVO Possible Causes
- Air leak after turbocharger
- Pipes between turbocharger and turbocharger control valve are loose, blocked, or damaged
- Pipes between turbocharger control valve and pressure servo are loose, blocked, or damaged
- Faulty turbocharger control valve
- Faulty pressure control valve pressure servo
- Sticky boost pressure control valve
How is the P1238 VOLVO code repaired?
Start by checking the “Possible Causes” listed above. Visually inspect the wiring harness and associated connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
Technical Notes
The first step is to check for an air leak after the turbocharger.
Possible Symptoms
- Engine light on (or service engine soon warning light)
P1238 VOLVO Meaning
The O1238 code will be set if the engine speed is above 3500 and the engine is operating under high load, the control signal to the turbocharger control valve is at maximum, and the pressure sensor pressure is below approximately 2.9 psi under normal boost pressure (signal too low). If the mass air flow sensor mass is above the desired value (signal too high), this is interpreted as a fault by the Engine Control Module (ECM). When the code is set, a reduction in boost pressure is used as a substitute value.