This is a generic powertrain diagnostic trouble code (DTC) applicable to all turbocharged vehicles. Vehicle makes may include but are not limited to VW, Dodge, Mercedes, Isuzu, Chrysler, Jeep, etc.

The powertrain control module (PCM) monitors boost pressure with a sensor called the manifold absolute pressure sensor (MAP). Understanding how a MAP sensor works is the first step in explaining the cause of P0237.

The PCM sends a 5 volt reference signal to the MAP sensor and the MAP sensor sends a variable voltage signal back to the PCM. When boost pressure is high the voltage signal is high. When boost pressure is low the voltage is low. The PCM uses the boost control solenoid to control the amount of boost pressure that is produce by the turbocharger while at the same time using the boost pressure sensor to verify that the boost pressure is correct.

This code sets when the PCM senses a low voltage signal indicating low boost pressure when a high pressure command has been sent to the boost control solenoid "A".

Symptoms of a P0237 code may include:

Because of the increased chance of catalytic converter damage and turbo over boost when P0237 is present it should be corrected before continuing to use the vehicle.

Potential causes for this code to set are:

Before diagnosing P0237 be sure there are no other trouble codes present in the PCM memory. If there are other DTC’s present, they should be checked first. Any codes related to waste gate control or 5 volt reference will induce the conditions necessary to set this code. In my experience the PCM is the least likely cause of this problem. More often than not it is chafed or burnt wiring near the turbocharger causing shorts or opens in the circuit.

A good starting point is always to check for technical service bulletins (TSB) for your particular vehicle. Your issue may be a known issue with a known fix put out by the manufacturer and can save you time and money during diagnosis.