Protect your investment with the high quality transmission skid plate and catalytic guards by RCI Metalworks. It's worth checking into.Underbody damage is costly. Many manufacturers give a five year, unlimited mileage warranty on these items. So if you have a newer car but it's out of it's bumper-to-bumper warranty, there still may be warranty on this type of problem. One thing to note is that many vehicle manufacturers offer a longer warranty on emissions-related parts. * Inspect the downstream heated oxygen sensor (HO2), replace if necessary The waveform of the sensor behind the converter should be more steady). * Use a scope to diagnose the oxygen sensor operation (Tip: The oxygen sensor in front of the catalytic converter normally has a fluctuating waveform. * Check for exhaust leaks at the manifold, pipes, catalytic converter. Some suggested steps for troubleshooting a P0420 code include: * The oxygen sensors in front and behind the converter are reporting too similar of readings * Damaged or leaking exhaust manifold / catalytic converter / exhaust pipe * The engine coolant temperature sensor is not working properly * An oxygen sensor is not reading (functioning) properly * Leaded fuel was used where unleaded was called for You will likely not notice any drivability problems, although there may be symptoms.Ī code P0420 may mean that one or more of the following has happened: It is part of the vehicle emissions system. This is indicative of (among other things) a converter that is not working as efficiently as it should be (according to specs). Typically the P0420 code triggers the Check Engine Light if the readings of the two sensors are similar. The downstream O2 sensor reading should be fairly steady. When the vehicle is warm and running in closed loop mode, the upstream oxygen sensor waveform reading should fluctuate. The catalytic converter has an oxygen sensor in front and behind it. P0420 OBD-II Trouble Code Technical DescriptionĬatalyst System Efficiency Below Threshold (Bank 1) You have four catalytic converters, and the one that is giving you trouble is cat#1, the one on the passenger side.īefore you purchase, read this description of the trouble code. This video can help us see if the cats are bad Obviously they have not done exhaust work to realize how many cats go to a vehicle. First of all, I would stay away from that local repair shop.

2004 toyota 4 runner cat convertor