P1B90 Austin A90 Diagnostic Trouble Code

P1B90 Austin A90 code definition:
P1B90 is a kind of OBD-II Diagnostic P-Powertrain Diagnostic Trouble Code for Austin A90.

P1B90 Austin A90 is a DTC or a diagnostic trouble code. It is a check engine light code which indicates that the catalyst's system efficiency is less than the required threshold. In simple terms, it means that more pollution is added into the air than what was supposed to be because of your car. The spark should have a light tan color. If the sensor probe comes with white and chalky parts, this means it has been lagging between switching phases, and should be replaced.

Symptoms

Symptoms of a P1B90 Austin A90 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

Common Misdiagnoses

Control Module Throttle Actuator Position Performance Problem
Air Conditioning (A/C) Clutch Feedback Circuit High Voltage Problem
Cruise Vehicle Speed/Set Speed Difference Too High Problem
Kick-Down Switch Failed Short Problem
Park/Neutral Postion (PNP) Switch Circuit Engine Torque Signal Circuit Problem

Repair Processes :

Look for missing ground strap or a rusty ground where the fuel tank is grounded to the frame. Check for damage to the wiring harness connector. Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble. Look at the plug wires to make sure they are not burnt or laying on the exhaust.

Process Tips

Diagnostic trouble code P1B90 Austin A90 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 P1B90 Austin A90.

Fortunately, P1B90 Austin A90 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.