Turbo Boost Pressure Not Detected
The P1248 code indicates that the engine control module (ECM) has detected a lack of turbocharger boost pressure. This can be caused by a mechanical failure in the turbocharger, a boost leak in the intake system, a faulty boost pressure sensor, or issues with the wastegate or variable geometry turbo actuator. The ECM monitors boost pressure via the MAP or boost pressure sensor and compares it to expected values; when the actual pressure is significantly lower than commanded, this code is set.
01. Most Common Causes
- Boost leak in intake system (hoses, intercooler, gaskets)
- Faulty turbocharger (seized bearings, damaged compressor wheel)
- Malfunctioning wastegate or variable geometry turbo actuator
- Faulty boost pressure sensor or MAP sensor
- Clogged or restricted air intake or exhaust system
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Significant loss of engine power and acceleration
- Whistling or hissing noise from turbo area
- Excessive black smoke from exhaust under load
- Poor fuel economy
03. Step-by-Step Diagnosis
Step 1: Scan for additional codes and check freeze frame data.
Step 2: Visually inspect all boost hoses, intercooler, and intake pipes for leaks, cracks, or loose connections.
Step 3: Check turbocharger for shaft play, oil leaks, and proper operation of wastegate/actuator.
Step 4: Test boost pressure sensor and MAP sensor with a multimeter or scan tool.
Step 5: Perform a boost leak test using a smoke machine or pressure tester.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with this code as it indicates a significant loss of boost, which can lead to poor performance and potential damage to the turbo or engine if the underlying issue worsens.
How much does it cost to fix?▼
The cost varies widely depending on the cause. A simple boost leak repair may cost $50-$150, while a turbocharger replacement can range from $1,000 to $3,000 or more.