Turbocharger Boost Sensor A Circuit High
The P0238 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the turbocharger boost sensor (also known as the MAP or boost pressure sensor) that is higher than the expected range. This sensor monitors intake manifold pressure to optimize turbocharger boost. A high voltage reading typically points to a short circuit to power, a faulty sensor, or wiring issues. This can lead to incorrect boost control, potentially causing reduced engine performance or overboost conditions.
01. Most Common Causes
- Faulty turbocharger boost sensor
- Short circuit to voltage in sensor wiring or connector
- Corroded or damaged sensor connector
- ECM software or hardware issue (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration or hesitation
- Possible overboost or turbo surge
03. Step-by-Step Diagnosis
Step 1: Use an OBD2 scanner to confirm P0238 and check for other codes.
Step 2: Visually inspect the boost sensor connector and wiring for damage, corrosion, or shorts.
Step 3: Test the sensor signal voltage with a multimeter (should be 0.5-4.5V depending on boost).
Step 4: Compare sensor readings with a known good sensor or use a scan tool to monitor live data.
Step 5: If wiring and sensor check out, test the ECM's 5V reference and ground circuits.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as it can cause poor performance, limp mode, or potential engine damage from overboost. Have it diagnosed promptly.
How much does it cost to fix?▼
Typically $50-$150 for a new boost sensor plus labor. If wiring repair is needed, costs may be higher.