P2574 — Catalytic converter sensor circuit voltage too low

The engine control module detected a low voltage signal from the catalytic converter's ozone reduction sensor circuit. This usually means the sensor or wiring is faulty, or the catalytic converter is deteriorating and not working properly.

Common causes

The cause is almost always one of a few things. Here they are — P2574 rarely comes from anything outside this list:

• Faulty catalytic converter ozone reduction sensor
• Damaged or corroded sensor wiring or connectors
• Deteriorated or clogged catalytic converter
• Poor electrical connections in sensor circuit

Where to start

In the order a sensible mechanic would work — the cheap checks first, the expensive replacements only after:

1. Inspect and repair sensor wiring and connectors
2. Test sensor operation and replace if faulty
3. Check catalytic converter condition for damage or clogging
4. Replace catalytic converter if deteriorated

That is what holds for P2574 in general. From here it depends on your engine — tell me which car it is and what it does, and I will give you the steps for it: real procedures, torque figures and diagrams instead of general advice.