P051B Allard P1 Diagnostic Trouble Code

P051B Allard P1 code definition:
P051B is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Allard P1.

P051B Allard P1 is described as Intake Air Temperature (IAT) Circuit Malfunction. It's actually a general trouble code for a problem on IAT electrical circuit sensor, as it sends incorrect voltage input signals to the PCM. The PCM then uses this data to provide the right strategies for the fuel delivery and ignition timing of the engine.

Symptoms

Symptoms of a P051B Allard P1 diagnostic trouble code may include:

Diminished fuel efficiency
Fuel pressure too high
Malfunction Indicator Lamp (MIL) illuminated
Hesitation upon acceleration

Possible Causes :

A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.
Dirty air cleaner element Damaged DPF
Faulty IMRC actuator/sensor

Common Misdiagnoses

Vehicle Speed Output Circuit Problem
Cruise Control Servo Indicates Low Problem
A/C System High Pressure High Temperature Problem
PCM Stack Overrun Problem
Transmission Control Module Reprogrammable Memory Problem

Repair Processes :

Use the DVOM to test resistance and continuity on all system circuits if actuator and sensor resistance levels are in compliance with manufacturer's specifications. Look for damage to the tank indicating impact that may have damaged the fuel pump or sender.

Process Tips

Diagnostic trouble code P051B Allard P1 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 P051B Allard P1.

Fortunately, P051B Allard P1 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.