Sensed Parameter
- Catalyst Monitor AMT
Faulty Code
- P0420
Monitor Description
- Detects a catalytic converter with unacceptable amounts of oxygen storage capabilities
Critera and Thresholds
- Oxygen Storage Capability (OSC) Time Difference > 0.182 sec
OSC Time Difference = OSC Worst Pass
Thresh - OSC Compensation Factor * (O2S 2 Response Time - O2S 1 Response Time)
OSC Worst Pass Thresh = 1.820 sec
Secondary Parameters and Enabeling Conditions
- Engine speed > 1000 RPM for minimum of 34 sec since end of last idle period
Predicted catalyst temp > 345C, < 450C
Baro > 72.3 kPa
IAT between -20.5C & 80C
ECT between 70C & 125C
Idle < 45 sec
MPH < 3
Test attempted this trip < 12
-75 RPM < (Engine Speed - Desired Speed) < 150 RPM
Engine run time > 520 sec
Battery voltage > 9 V
Flow < 7 g/sec
Rapid Step Response Enable Criteria
OSC Time Difference Step > .590 sec
OSC Time Difference Step > 0.00 sec
None of the following DTC’s set:
105, 107, 108, 112, 113, 117, 118, 122, 123, 131, 132,
133, 134, 1133, 137, 138, 140, 141, 171, 172, 200, 300,
325, 336, 340, 341, 440, 1441, 442, 446, 452, 453, 480,
481, 502, 503, 506, 507, 601, 602, 1621
There is also a sedondary test ran which can also set this code. From what i am reading it just varies the thresholds and conditions too check the system again.
My head hurts now. So are you saying the computer is comparung the readings from the O2 sensor before the cat to the O2 sensor after the cat ? I had the cat replaced about 5,000 or 6,000 ago.
