DTC Description
- Fault Memory & Actuation Of MIL - After 2 consecutive driving cycles with fault.
- Frequency Of Testing - Continuous.
- Checked Signal Or Status - Voltage ratios (amplitudes) of O2 sensor signal after TWC to O2 sensor signal before TWC.
- Limit Value - O2 sensor signal after TWC is a maximum of 80 percent of O2 sensor signal before TWC.
- Duration Of Test - Approximately 170 seconds.
- Test Conditions - Engine speed approximately 1050-2400 RPM, engine load approximately 20-54 percent, TWC temperature more than 716°F (380°C), lambda control enabled and lambda more than 0.4 volts, no O2 sensor fault (aging, heater or signal) and no combustion misfires.
NOTE:
TWC is evaluated for its ability to store oxygen. Several measurements must be made in the specified engine speed and load range. The results are compared with a performance map and therefore any faults are recognized. The amplitude of the O2 sensor voltage after TWC must be less than that of the amplitude of the O2 sensor voltage before TWC (as an example, if TWC was empty, the O2 sensor signals would be identical before and after the TWC). If fault codes were issued for TWC and for the O2 sensor before TWC at the same time, first replace the O2 sensor before TWC. After replacing O2 sensor, if no TWC fault is recognized, the effectiveness of the TWC is slightly reduced, but it is not necessary to replace TWC yet.