87 bronco i have been online looking at these catalytic converters that say they replace both front and rear converters does that really mean i only need that one instead of the two?

Possible causes
- Warm Up Three Way Catalytic converter deterioration or malfunction
- Exhaust system leaks
- Loose front or rear HO2Ss
- Faulty front heater O2 sensor
- O2 sensors harness is open or shorted
- O2 sensors poor electrical connection
Tech notes
As the code description implies the P0422 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem. If the P0422 code is combined with other codes, try fixing the other codes first.

C1201 error code means that you have some problem in engine control system.

Possible causes for P0421 error

• Warm Up Three Way Catalytic converter deterioration or malfunction
• Exhaust system leaks
• Loose front or rear HO2Ss
• Faulty front heater O2 sensor
• O2 sensors harness is open or shorted
• O2 sensors poor electrical connection

The P0421 code means that the vehicle's control module has detected that the three-way catalytic converter is not working properly (is not as efficient as the factory is expecting). Replacing the oxygen (O2) sensors may sometimes fix the code, but in most cases the catalytic convert needs to be replaced to fix the problem.

It could have a weak or failing ignition coil. The other thing I can think to look for would be an exhaust restriction.. (clogged catalytic converter)

What about the fuel filter?? was it replaced?

plugged or bad catalytic converter, when my car surged while driving or at a stop it was a bad EGR Valve

Hi, P0420 code means a catalytic converter fault.
The catalytic converter has an oxygen sensor in front and behind it. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The downstream O2 sensor reading should be fairly steady. Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). It is part of the vehicle emissions system.

• Check for exhaust leaks at the manifold, pipes, catalytic converter. Repair as required.
• Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. The waveform of the sensor behind the converter should be more steady).
• Inspect the downstream heated oxygen sensor (HO2), replace if necessary
• Replace the catalytic converter

P0432 - Main Catalyst Efficiency Below Threshold Bank 2
The ECM or PCM monitors the front an rear O2 sensors. The ECM or PCM detects Warm up Catalytic Converter when the sensors are out of specifications.

DTC is set when the ECM or PCM detects rear HO2S value difference becomes closer to value of front HO2S. The ECM or PCM monitors when vehicle speed is 25-60 MPH, load is 22-45 percent and engine speed is 1000-3000 RPM.

Symptoms
- Engine Light ON (or Service Engine Soon Warning Light)

Possible causes
- Warm Up Three Way Catalytic converter deterioration or malfunction. - Exhaust system leaks. - Loose front or rear HO2Ss. - Front HO2S malfunction. - O2 sensors harness or connectors

Possible solution
- Replaced Catalytic Converter - Replaced rear O2 sensor - Repair wire harness or connectors

Check it ans tell us news.

measure fuel flow and flow VOLUME. Plugged filters and tank strainers are suspect.

You should have changed the front o/2 sensors if any. The rears just read what the cats are doing and the fronts control the fuel feeds to the engine. Using Aftermarket cats is usually a hit or miss prop on the p0420. U need to find a shop that can really diag this for you because it sounds like only one bank is coding for you therefore bank 2 is ok. Go to IATN.com and find a good mechanic.

A muffler shop should be able to replace just the converter

My 88 fullsize w/351W uses two cats.