i have a 2000 civic ex Auto STOCK 2 weeks ago the exhaust piping split cause it was really rusted have gotten it fixed but i suspect there may be another leak because i still smell fumes when i come to a stop, Today CEL came on this morning and i got these 5 codes : p0171, p0137, p0138, p0420, p1457 if i find another exhaust leak would that clear all these codes?
P0171 Fuel System Too Lean
P0137 Secondary Heated Oxygen Sensor (Secondary HO2S) Circuit Low Voltage
P0138 Secondary Heated Oxygen Sensor (Secondary HO2S) Circuit High Voltage
P0420 Catalyst System Efficiency Below Threshold
P1457 Evaporative Emissions (EVAP) Control System Leakage (EVAP Canister System)
The # after the "P" [0 or 1] tells you if its a generic  or manufacturer specific  code.
An exhaust leak maybe but this maybe the cause of a bad Catalyst Converter and O2 sensors. This is just my guess though, maybe someone else could chime in.
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