P172B Diagnostic Trouble Code

P172B is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a P172B diagnostic trouble code may include:

Fuel pressure too low
Rich or lean exhaust
Diminished fuel efficiency
Reduction in engine performance, especially at low RPM levels

Possible Causes :

A faulty oxygen sensor. This will set a code in itself, however, a faulty oxygen sensor does not automatically condemn the sensor. The code just means that the sensor signal was not within specifications. An air leak or any of the above will cause an erroneous signal. There is a multitude of O2 codes relating to O2 performance which gives a clue to the problematic area.
Some aftermarket accessories and performance modifications
Faulty IMRC actuator/sensor

Repair Processes :

With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Now, clear the codes and test-drive the vehicle to see if the code is reset.

Process Tips

Diagnostic trouble code P172B is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before P172B.

Fortunately, P172B is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P172B Trouble Code For Specific Cars

P172B Ferrari 801 Intake Valve Control Solenoid Circuit Range/Performance (Bank 2)
P172B Chrysler Neon Evaporative Emission Control System Vent Control Circuit Malfunction
P172B Ssangyong Tivoli Lamp Headlamp Input Circuit Open
P172B Peugeot Peugette Engine Coolant Temperature Circuit High Input
P172B Skoda Polular Knock Sensor 2 Circuit Low Input (Bank 2)
P172B Holden Combo Pedal Position Sensor C Circuit High Input
P172B Royce 1904 Ignition Retard Request Circuit Fault