1, 2 and 3 Digit Codes: 112

Trouble Code Number
- Scan tool 112
- General scan tool P0422
- MIL 64

Fault Message
- Catalytic Converter Efficiency Failure

Background
- During normal closed-loop operation, the PCM monitors the catalytic converter for hydrocarbon conversion (HO) efficiency.
- When HO conversion drops below 60 percent efficiency, the PCM stores a diagnostic trouble code.

Range of Check
- Engine coolant temperature greater than 76°C (170°F)
- Vehicle speed greater than 20mph for 2 minutes
- Open throttle
- Closed loop operation
- Engine speed between 1248 and 2400 r/min
- MAP voltage between 1.50 and 2.60 V

Set Condition
- The switch (Lean/Rich) rate of the rear heated oxygen sensor reaches 70% of the front sensors switch rate.

Probable Cause
- Catalytic converter failed
- Exhaust manifold failed (leaks)
- Wiring harness/connector failed
- PCM failed