Turbo Boost Sensor A Circuit High Input
The P0238 code indicates that the Engine Control Module (ECM) has detected a voltage signal from the turbocharger boost pressure sensor (sensor A) that is higher than the expected range. This typically points to a short to voltage, a faulty sensor, or wiring issues. The boost sensor monitors intake manifold pressure to regulate turbocharger operation; an abnormally high reading can cause the ECM to limit boost or trigger limp mode.
1. Most Common Causes
- Faulty turbo boost pressure sensor
- Short to voltage in sensor signal circuit
- Damaged wiring or connector
- ECM internal fault (rare)
2. Symptoms You Will Notice
- Check Engine Light illuminated
- Reduced engine power or limp mode
- Poor acceleration
- Excessive black smoke from exhaust
3. Step-by-Step Diagnosis
Step 1: Use a scan tool to verify P0238 and check freeze frame data.
Step 2: Visually inspect the boost sensor connector and wiring for damage, corrosion, or shorts.
Step 3: With key on engine off, measure voltage at sensor signal wire; should be ~0.5-1.5V. If >4.5V, suspect short to voltage.
Step 4: Test sensor by applying vacuum and monitoring voltage; replace if out of spec.
Step 5: Clear code and test drive; if code returns, check ECM for internal issues.
4. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive long distances as the vehicle may enter limp mode, reducing power and potentially causing unsafe driving conditions. Immediate diagnosis is advised.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for a new boost sensor and labor, but can be higher if wiring repairs are needed.
5. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.