Boost pressure sensor
Definition
The boost pressure sensor measures absolute pressure in the charge air pipe or manifold after the turbocharger, often combined with an intake temperature sensor (T-MAP), and gives the ECU the feedback it needs to regulate the wastegate or VGT vanes. Typical range is 0.5-3 bar absolute with a linear 0.5-4.5 V output; with the engine off it must match atmospheric pressure. Oil mist and soot coat the element and make it slow or offset, which the ECU reads as under- or overboost and answers with limp mode. A boost leak or sticking turbo actuator looks identical in the data, so compare requested vs. actual boost and inspect pipes before condemning the sensor. Codes: P0235-P0238 (sensor circuit), P0299 (underboost), P0234 (overboost), P0236 range/performance, P0068 (MAP/MAF/throttle correlation).
Codes often stored
- P0068MAP/MAF - Throttle Position Correlation
- P0234Turbocharger/Supercharger 'A' Overboost Condition
- P0235Turbocharger/Supercharger Boost Sensor "A" Circuit
- P0236Turbocharger/Supercharger Boost Sensor "A" Circuit Range/Performance
- P0237Turbo/Super Charger Boost Sensor 'A' Circuit Low
- P0238Turbo/Super Charger Boost Sensor 'A' Circuit High
- P0299Turbocharger/Supercharger 'A' Underboost Condition