P0720, PO501, PO141 1996 Honda Accord howdo I fix problems associated with these codes?

Question

All three codes came up on SMOG Check. Are they connected and how can they be repaired?

Answer 1

P0720 Problem in the counter shaft speed sensor circuit

P0501 VSS (vehicle speed sensor ) circuit range / performance

P0141 02 heater sensor circuit malfunction

The code you have being a countershaft and a vehicle speed sensor,  This vehicle in design does not use a vehicle speed sensor what it uses is a countershaft sensor, this is known has a NC signal to calculate speed which operates as the speed sensor so you only have 2 code to deal with, If the speedometer is not working this is why it would code a P0501. 2 items that is required for the fix the counter shaft sensor and the down stream 02 sensor, When a 02 sensor fails it is usually  due to age and mileage its heater circuit is usually the first to degrade.