Is there a more accurate test than a code reader?

I recently got like 6 codes on my Tacoma 06. Most are leading to a bad converter or 02 sensor. Is there a more accurate test to tell you exactly what it is?

 

Post your codes. ETCs just point you a direction, they are not detailed failure points.

 

P0420 requires you to graph the o2 and a/f sensor readings. Typically P0420 0430 only triggers if its failed.

 

You need to determine what the freeze data code is that will give you the proper direction into which you need to investigate first.

TYPICALLY unless high mileage is a factor, if a cat converter is failing, there is a reason why it is failing. Usually it is due to overly lean activity for an extended period of time on one or both banks.

 

My P0420 was caused by a bad gasket.

 

Tacoma 2006, over 400k. These were the codes that came up.

P0430
P0174
P0171
P0420
P0455
P0441

most are pointing to the catalytic converter, lean bank, and evap leaks. You guys any ideas where to start?

 

There are other conditions that will throw these codes that do not require replacing Cats. But people don't like hearing that...

Both good tools to help figure it out!

Torque app(Android) and an inexpensive OBDii adapter will let you graph readings.

 

Evap leaks are probably going to be the easiest and cheapest, which could clear up the lean code and in turn clear up the cat code

 

Start with the most probable cause.

Another path is to begin replacing/repairing simple stuff working your way to the more complex.

400K is a boat load of miles. I'd suspect everything under the hood will need service of some sort.

 

Please don't start throwing parts at it for no reason, checking AFr/O2/Fuel trims is simple and cheap and gives a world of info.

 

Agreed. Its another path. Not an efficient path.

 

So your codes are:

P0430 Catalyst System Efficiency Below Threshold (Bank 2)
P0420 Catalyst System Efficiency Below Threshold (Bank 1)
P0441 Evaporative Emission Control System Incorrect Purge flow
P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)
P0455 Evaporative Emission Control System Leak Detected (Gross Leak)

Looking at this from an analytical point of view, you have the same code on both cats and a system lean condition on both banks as well as evap codes, soooooooo… do we have one, two or thee different problems here? I'm betting one. As mentioned, the evap system effects everything downstream, in other words, both engine banks. If you had a fuel trim or cat issue, it is unlikely that the same codes would pop up for both banks at the same time. So, let's for the moment, assume that the cat and trim codes are a result of the evap issue. There, we have two codes, one for incorrect flow, and one for gross leak.

It's also fair, for the sake of trouble-shooting to say that a flow-rate issue is likely to be caused by a gross leak I think, so really, what this probably comes down to is a compromise in your evap system. Now, we have to find out where... the first and easiest place is your gas cap. You can either replace it, or just seal it up with some tape, clear the codes, go for a drive and watch your fuel trims. If they fall into line and the codes don't return, that was it... easy, peasy. In my experience though, it's rarely that simple.

My bet would be either the vent or purge valves. You need to track that down (sorry, I don't know the locations on your vehicle), get a wiring diagram and test them. If one is bad, replace it. If not, then you likely have a failed/damaged line. The best way to find these is with a smoke machine. You can either take it to a shop, or if you don't mind spending $20 to get a cool tool, you can build your own - lots of instructions on YouTube. Introduce the smoke into the system and watch to see where it escapes.

 

To add on to this if you determine that the converter is bad, it is HIGHLY advisable due to the cost of a replacement catalytic converter and the labor involved in replacing it on a 2nd gen (especially true on a later gen 2012+) that you correct the running condition before replacing the cat converter otherwise it will fail in short order leaving in you the same predicament that you started in.

As previously mentioned STFT/ LTFT inspection is a very important tool to utilize in making sure running condition is good. On most Toyotas +-5.5% fuel trims are good. Anything over that you should inspect. Make sure vacuum leaks are not a factor as well. A smoke machine is highly helpful if you have access to one. Also, check spark plugs and air fuel sensor readings. Any of the items I discussed above are usually the factors affecting catalytic converter failure and their failure is usually marginal at most but enough to kill a high mileage converter. If they go blatantly bad, early failure is more the norm.

One more thing, a fuel pump failing to maintain spec pressure can contribute to lean activity. Sometimes it's best to check that as well if you see lean activity.

 

I appreciate you guys all answering with detail responses. I was looking into what you guys were mentioning and came across this.... an air valve with no hose....you guys happen to know what this is connected too?

 

Nothing. That's a outlet that is not used on that solenoid.

 

I’m running these codes P0430(1)
Bank 2 says it’s emergency to fix or will create additional damage.

P0430(1)
P0420
P0430 Bank 2

 

Investigation and probable repair coming up.

 

400k miles, no matter what happens, you got your money's worth. Good suggestions for you already. For $5 app and $20 OBD transmitter, Torque Pro is worth it. Your engine has a lot of miles so a lot of potential problems. Start with the cheap stuff and work your way up. Bottle of soapy water and rag; spray on those old vacuum lines and look for bubbles. Wipe it off and look for problems when things are a bit cleaner.
Not sure how long you expect the motor to last, but....

 

Check if the vacuum hose or the plastic piece where it connects to the right of the throttle body is cracked. On my truck the plastic piece cracked and caused the codes for a vacuum leak and lean fuel on both banks to pop up on my truck. If has broken off like mine then you can just super glue it back in place.

 

I'd check these codes first before addressing the P0420,P0430 codes
P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)

Hints:


P0420 - P0430


As suggested above, the Cat Converter Inefficiency codes doesn't necessarily suggest to automatically replace the cat converters. Sometimes a leaky exhaust system is able to inject un-metered air into the exhaust system (exhaust pulse) which can confuse o2 senser readings. Or, a faultering o2 sensor(s) can also confuse the readings.