U1943 Standard Ensign Diagnostic Trouble Code

U1943 Standard Ensign code definition:
U1943 is a kind of OBD-II Diagnostic U-Network Diagnostic Trouble Code for Standard Ensign.

U1943 Standard Ensign is defined as Cylinder 3 Injector Circuit Malfunction. This code means the PCM (powertrain control module, also known as ECM or engine control) has detected a problem in the injector or its wiring, or in injector circuit for cylinder 3. If the car doesn't start, they will proceed by testing the voltage at the fuel pump connector and see if the fuel pump relay, fuse, and PCM circuitry should be inspected.

Symptoms

Symptoms of a U1943 Standard Ensign diagnostic trouble code may include:
Place of U1943 in engine

Possible Causes :

  • The Mass Airflow sensor will also cause this problem. Mass Airflow circuit malfunction.
  • Fuel with a large percentage of sulfur will clog the DPF quickly
  • An air leak forward of the DPF will change the sensor readings resulting in the code

Common Misdiagnoses

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

Repair Processes :

Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed.

Process Tips

Diagnostic trouble code U1943 Standard Ensign 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 U1943 Standard Ensign.

Fortunately, U1943 Standard Ensign is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

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