2743
Moderate2743 — Cylinder 3 Misfire: Catalytic Converter Damage Risk
Description
What the code means
2743 is set by the engine control module (DME) when it detects misfires in cylinder 3 that risk damaging the catalytic converter: unburned fuel enters the exhaust and burns inside the converter, overheating it. The code is similar to 274E.
To protect the converter, the DME may cut fuel delivery to the affected cylinder. Severity is moderate, but don't put off diagnosis: driving with misfires directly threatens the catalytic converter.
Symptoms
Symptoms
- Engine misfires, rough running, especially noticeable at idle;
- loss of power;
- Check Engine light on the instrument cluster.
Causes and fixes
Diagnosis and repair
- Pin down the cause of the misfires: swap the cylinder 3 ignition coil to another cylinder and check whether the fault follows the coil;
- Check the cylinder 3 spark plug;
- Check the cylinder 3 fuel injector;
- Replace the faulty component (coil, plug, or injector);
- Clear the codes and confirm the misfires don't return — that confirms the repair worked.
Possible secondary damage
Secondary damage
- Catalytic converter damage from unburned fuel burning inside it;
- failure of the oxygen sensor working in a contaminated exhaust stream.
Ignoring the fault takes you from misfires to a destroyed catalytic converter and failed O2 sensors, so get the repair done promptly.