Q: p0420
Prizm has P0420 as of today here is the timeline -Rebuilt engine two years ago -Change Cat last year when smog test came around -Last few months I had the P0171 and P0300, P0302, P0304 -Replaced MAF sensor, TPS sensor, O2 upstream sensor, Manifold Gasket, Spark plugs, and Fuel injectors - after replacing those parts the only code (stored & pending) that showed was P0420 -Just changed the Downstream 02 sensor but P0420 still pops up
Symptoms
- LTFT has 14.0
- RPM drops (car shakes a little) to the 600s when the car is in neutral or in a stop.
- Noticed the rpm drops when the cooling fan turns on
Any suggestions
My car has an automatic transmission.
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