U3243 Subaru M80 Diagnostic Trouble Code

U3243 Subaru M80 code definition:
U3243 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Subaru M80.

U3243 Subaru M80 is defined as Camshaft Position Sensor A Circuit Low. This means the CMP (camshaft position) sensor circuit on engine bank 1 sends an irregular reading. Other symptoms that may indicate this problem are when the Check Engine Light illuminates and when there is a visible lack of engine power.

Symptoms

Symptoms of a U3243 Subaru M80 diagnostic trouble code may include:

The engine oil will exhibit dilution from the ECUs attempts to increase engine temperature. Some vehicles advance the fuel injection timing slightly after top center to afterburn a small amount of fuel to increase exhaust temperatures. Some of this fuel enters the crankcase. When the ECU determines the necessity to regenerate the DPF, the service life of the oil be shortened significantly
Faulty or damaged wiring
Hesitation upon acceleration
Engine surge

Possible Causes :

Some aftermarket accessories and performance modifications
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.
Defective ECU strategies or components will prevent proper regeneration

Common Misdiagnoses

TP Sensor Learn Not Complete Problem
Low Coolant Circuit Problem
Cruise Control System - Vehicle Accel Too High Problem
TFP Valve Position Switch-Drive Without Drive Ratio Problem
Problem

Repair Processes :

Look at the plug wires to make sure they are not burnt or laying on the exhaust. 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. If you find a related TSB, the information will often help in diagnosing the code in question as TSBs are crested from many thousands of repairs.

Process Tips

Diagnostic trouble code U3243 Subaru M80 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 U3243 Subaru M80.

Fortunately, U3243 Subaru M80 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.