Catalyst Efficiency Below Threshold--
#11
RE: Catalyst Efficiency Below Threshold--
ORIGINAL: finch13
I'm going to have to argue that one. My 1999 has had the P0420 Cat Below Threshold code since 2001, that's 7 years with the code and has not suffered a loss in mileage. In fact, the other week I got 34 MPG.
I'm going to have to argue that one. My 1999 has had the P0420 Cat Below Threshold code since 2001, that's 7 years with the code and has not suffered a loss in mileage. In fact, the other week I got 34 MPG.
Considering the secondary O2 sensor is located downstream of most of the catalyst, it's not evenmeasuring the proper thing to close the fuel-control loop.
#13
If you got dtc P0420, the problem is not likely the secondary O2 sensor but the catalytic converter.
If you have a scanner you can check the secondary (behind converter) voltage trace for faulty converter operation (frequent 1-2 hz, voltage swings from 0.1 -0.9 volts. If that pattern is present the converter has failed.
Or you can simply replace the secondary O2 sensor and see what happens,
good luck
If you have a scanner you can check the secondary (behind converter) voltage trace for faulty converter operation (frequent 1-2 hz, voltage swings from 0.1 -0.9 volts. If that pattern is present the converter has failed.
Or you can simply replace the secondary O2 sensor and see what happens,
good luck
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67.............P0420.............................. ...............Catalyst system efficiency below t
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