Question about Cars & Trucks
Code po420 but cat is functioning according to smog paper work, cleaned air flow meter with correct cleaner, checked 02 sensor data, found sensors switching, did not check sensors while vehicle was cold, test drove vehicle and code returned first drive cycle. i was told i needed to replace cat and than told to replace the air flow meter please any info would be appreciated thanks
You don't check O2 Sensors when cold,
they won't be operating or switching until
the computer goes into closed loop & converter
lights off at 600 degrees & continues to hopefully
around 900 to 1,100 degrees
Other than replacing a sensor, the only real
test I found of any value, is to watch switching
times on an oscilloscope
You can, as you said, look at scan tool data
Giving your vehicle is a 2003 & converters last
12 to 14 years, you know yours is worn out,doesn't
matter what the inspection gas results were & with
any codes, you should have been rejected & not tested
If you check fuel trim,you will see how well the MAF Sensor
is doing & you can't adjust fuel if the converter is not capable
of holding oxygen for the sensors to read
The front O2's get replaced on all vehicles at 100,000
when or before they slow down & fail
Posted on Jul 10, 2013
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Posted on Jan 02, 2017
Catalyst Effeciancy below threshold (Bank 1) is the code meaning. Check or replace the oxygen sensors. Some cars have 2 .One is on the front of the cat. the other is the on the back. Check the back sensor . Other possible causes are leaking or damaged exhaust manifold, bad coolant temp sensor.If toyota did not replace both . replace the one on the back of the Caty.
Posted on Feb 02, 2009
The only thing that will set this code is the catalytic converter or the oxygen sensor behind it. Way to tell if it is the sensor is to monitor voltage reading with scan tool and see if it is fluctuating the same as the upstream oxygen sensor. If it is the converter is "free flowing" and will have to be replaced. If the sensor is "flatlined" then it is most likely bad and setting the code.
Posted on Apr 30, 2009
I had the same problem, then took my car to an expert repair shop who diagnosed the sensors and
found no problem with the car. They notified the DMV who was unaware of the problem, who then told the repair shop (John's Bascom Automotive) that they will adjust their computer system to allow a "two speed idle test". My bill was $95 and I still have to pay for a smog test after driving around for
a couple of days to clear the computer monitors, a fair amount and I gladly paid it.
John advised me that I'd get no satisfaction with Toyota or the DMV. I went to the dealership where I
bought the car and they said that the smog stations don't know what they're doing. They charge
about $100 and work around the P0500 code but it takes them about two hours to do this. I told
them that I should have been notified about the dyno none-compatability by Toyota and that Toyota
should have notified the DMV beforehand. I wonder how many speed sensors are being replaced by
unknowing smog shops around the state. I got Toyota's main customer support phone number and
will call them Monday. I'm going to get my pound of flesh ($95 worth) from the DMV next week also.
Posted on Jun 26, 2009
OK. Since you have had so much trouble lets check the dealer for an updated software calibration for the PCM (power train control module). Once we're sure there is no "fix" here lets talk about "lean" engine conditions. Lean means one of two things are wrong with the air fuel mixture (ideally 14.7 parts air to 1 part fuel). 1. Too much air -or- 2. Not enough fuel. If you access to a scan tool we need to look at fuel trims. With the engine warm look at this data on the scan tool. You have a "bank 1" and "bank 2" fuel trim data. Additionally, each bank has a long term and a short term value. With the Engine hot and at idle add the LT and ST trim value for bank1 and write it down...do the same for bank2. Repeat this step, for EACH bank with engine at 2500 RPM in park (hold at 2500 for at least 30 seconds so trims update). Now, you have the total trim values for each bank at idle and at 2500 RPM. What should the values be? Total trim +/- 5 is good, +/- 10 borderline any thing greater is code setting territory. If trim numbers are high at idle and in range at 2500 rpm you have a vacum leak behind the mass air flow sensor. Or a faulty MAF. Pay particular attention to the air inlet hose clamps behind (between MAF and engine) the MAF. Also use ford parts only.
Posted on Nov 14, 2009
First I would try resetting the ECU by disconnecting the battery for a few minutes. This will remove the code. Then see if it comes back. Mind you you will not pass inspection, because the ECU will need to monitor a certain amount of driving "cycles" before inspection will accept the findings. Before that, replace your O2 sensors, and get those out of the way. P0770 is a Shift Solenoid E Malfunction. You will have to look at a manual to find out which Shift Solenoid that "E" refers to and where it is located. TC lockup, refers to the TC lockup solenoid. If so I would try replacing that and going from there. The auto transmission is a pretty complicated beast, and even the most experienced DIY'ers would go past the normal maintenance. HOWEVER, changing solenoids is considered, at least to me, DIY maintenance. Whats is your RPM when cruising at say 60 mph. If its more than 2400 rpms, then i would say it is your lockup solenoid. hope this helps
Posted on May 31, 2010
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