The MAP sensor has a 5-volt reference signal, which is supplied by the PCM, then the MAP Sensor directs a variable voltage signal to the Powertrain Control Module (PCM). If the boost pressure is high, the voltage signal is also high. If the boost pressure is low, the voltage signal is also low. Also, the PCM uses a solenoid to control the amount of boost pressure produced by the turbocharger. The MAP sensor also verifies that the boost pressure is right.
If the PCM detects a voltage signal indicating low boost pressure, even though a high-pressure command has been sent to boost control solenoid “A”, the DTC code P0237 OBDII is set.
The establishment of the diagnostic code P0237 OBD2 is due to the following reasons:
The air filter could be clogged.
Damaged cables leading to the Manifold Absolute Pressure (MAP) Sensor
The MAP sensor may be defective.
Leaking exhaust manifold.
Faulty internal turbocharger components.
Possible solutions of the DTC code P0237 Generic
The steps to solve the problems of the fault code P0237 OBDII are:
Look for Technical Service Bulletins (TSB).
Check the electrical connections, the cables may be defective. Also, check the terminals of the connectors and verify that they are not corroded. Repair or replace them if necessary.
With the key in the on position and the engine off, test the reference cable of the Manifold Absolute Pressure (MAP). Check to see if the 5 volts are present. If so, the booster probe should be between 0.2 and 0.5 volts. If not, the MAP sensor must be replaced.
With the DVOM connected, start the vehicle and with a vacuum pump, apply vacuum to the turbocharger's wastegate intake engine. The voltage should increase, if it does not, the turbocharger may be defective.