Got code po 421 - 1999 Mitsubishi Mirage

101,380 and 118. These together is a no start. Take it to a garage. Just a guess, but I would be looking into the wiring. You waited to long to have a problem fixed. One bad part over time will lead to many codes. The PCM is trying to adjust to make the engine run right. Throwing other sensor out of range. Out of range pops a code.

the p0421 code on this vehicle is either caused by a bad catalytic converter or an oxygen sensor. your mechanic has a scan tool that he can verify if the converter is faulty by comparing the rear o2 sensor to the front sensor. If the rear o2 sensor's voltage is switching from rich to lean (01-1.0v) similar to the front's, then, it's a bad converter. The rear o2 sensor should keep a steady voltage reading. Have him do this test while at cruising speeds. good luck

You can't fix these types of complex electronic engine control problems without special equipment.

Forget to write it down?

Generic or Manufacturer?

There are 41 Generic O2 Codes

PO 131--bank 1 sensor 1
PO 137--bank1 sensor 2
PO 143--bank1 sensor 3
PO 151--bank2 sensor 1
PO 157--bank1 sensor2
PO 163--bank2 sensor 3

These codes are making me lean towards the ignition coil pack.My stepson's 2001 Sable 3.0 v6 had one cylinder misfiring(5-code P0305),which shares a coil with cylinder 1(code P0301).I diagnosed it by trading wire 1 and 5 at the coil,and the code changed to P0301.You have codes for the two cylinders on the same coil,so this is most likely it.(these codes would also trigger P0300(Multiple Misfires Detected) and P0316(Misfire Detected First 1000 Revs)).

PO 134 = 02 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 1 SENSOR1)
PO 153 =02 SENSOR CIRCUIT SLOW RESPONSE (BANK 2 SENSOR 1)
PO 154 =02 SENSOR CIRCUIT NO ACTIVITY DETECTED (BANK 2 SENSOR 1)
PO 155= 02 SENSOR HEATER CIRCUIT MALFUNCTION (BANK 2 SENSOR 1)
PO 171= SYSTEM TOO LEAN (BANK 1)
PO 174= SYSTEM TOO LEAN (BANK 2)
I WOULD SAY YOU HAVE FAULTY OXYGEN SENSORS CAUSING THE ENGINE TO RUN TOO LEAN REPLACE THEM AND YOU SHOULD BE BACK IN BUISNESS

hi p -codes are as follows po 301 cylinder 1 missfire detected
po 304 cylinder 4 missfire detected
po 335 crankshaft position sensor A circuit malfunctio
po 750 shift solenoid A malfunction

check oxygen sensors first

P0421 - Warm Up Catalyst Efficiency Below Threshold (Bank 1)
P0171 - Fuel System Too Lean - (Bank 1)
P0446 - Canister Close Valve Malfunction
P1191/P1193 - Limp Home Valve - Low RPM
Before replacing the catalytic converter (bank 1 next to the firewall, Bank 2 is near the radiator), you'll want to verify it is bad (most likely is it sinse you also have a 'lean' code for Bank 1 - probably clogged). This can also cause misfires and engine stumble (low RPM) that's probably where the 1191/1193 occurred. The final DTC, P0446 - Canister Close Valve Malfunction, could be the valve itself, or the wiring between it and the PCM. Check the connector & pins for any damage/corrosion.

Hope this helps

djjfkg