P0551 Lexus Ls 300 Diagnostic Trouble Code

P0551 Lexus Ls 300 code definition:
P0551 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Lexus Ls 300.

P0551 Lexus Ls 300 is described as Oxygen Sensor Circuit No Activity Detected (Bank 1, Sensor 1). This means there's a problem in the front oxygen sensor on Bank 1, as the O2 sensor is inactive. 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 P0551 Lexus Ls 300 diagnostic trouble code may include:

Lack of power
Faulty O2 Sensor
Poor acceleration
Rich or lean exhaust

Possible Causes :

Faulty IMRC actuator relay (if equipped)
A large air leak at or near the number one oxygen sensor would also cause a lean mixture.
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.

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 :

It should be pretty close to battery voltage (12 volts). If not, then this is the circuit that has the problem. 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.

Process Tips

Diagnostic trouble code P0551 Lexus Ls 300 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 P0551 Lexus Ls 300.

Fortunately, P0551 Lexus Ls 300 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.