2007 T4 Fault code help?

P0420 frequently occurs when: i.) O2 sensors are bad; or ii.) catalyst is bad. Often root cause of bad sensors/catalyst is excessive oil consumption fouling catalyst and/or sensors. In my 2006 Gen2, I have done the following to avoid P0420 CEL: i.) installed after-market catch-can to capture spoils from EGR system (thereby preventing such spoils from being feed back into the motor and fouling sensors and catalyst); ii.) changed oil change interval to 3500 to 4000 miles; iii.) never filling oil level above half way point on dipstick between full and add-oil (IOW use 3.5 quarts of oil when doing oil change); and iv.) using straight 40W oil (I use Shell Rotella straight 40W - Shell also makes a straight 40W for diesel applications (not what I am using currently)).

Since making the above changes about 5 months ago, no more P0420 CELs (except one instance where the catch-can became full and I did not timely empty it). The more miles you have on the engine, the more likely the rings are worn. Worn rings create blowby (can be thought of as crankcase pressure creator). When the motor's crankcase (AKA oil pan) is filled with an oil level above the half way point on dipstick (between full and add-oil). Oil level above the half way point on dipstick causes excessive oil mist to be created by crankshaft weights contacting oil in the oil pan. Blowby then forces oil mist to be circulated through the PCV system and ultimately back into the motor through vacuum port adjacent to the throttle body.

PS Spoils removed by catch-can typically include unburnt-fuel, water condensation and oil mist (oil mist in engine is usually condensed into both: a.) plain oil, and b.) also mixed into an emulsion with the water). We have all been told that oil and water do not mix. Oil water NOT mixing is the general rule. However, there is an exception: emulsions. When the oil mist is mixed with the water condensate, an emulsion is formed (similar emulsion as formed by a blown head gasket). My theory is that the catalyst has an extremely difficult time burning off such an oil/water emulsion. Thus, the solution, IMHO, is to prevent the oil/water emulsion from reaching the combustion chamber (by inserting an oil catch can between the PCV valve and the throttle body vacuum port).

PPS Remember, mayonnaise is an emulsion consisting of oil and a water based protein (egg).

 

How much oil are you burning currently?

What is your oil change interval?

What weight/type of oil are you using?

 

I wouldn't worry about the history codes. They are just that history, so not a current problem.

You need to take a look at your 12 V battery and ensure a) it is fully charged and b) in good serviceable condition. You will need to continue to monitor the health of your 12 V battery otherwise you could be chasing your tail looking to solve problems caused by an unreliable power supply. If it is at all looking like it is or soon will be unreliable, you will need to replace it if you want to do any further diagnosis, should that be necessary. It needs to be tested with a good load that proves it stays above 10 V.

Primarily I am advising this as both the C2300 and the C2318 is indicative of problems with the parking actuator which may be caused by low voltage received at the terminal +B voltage of the transmission control ECU That is, the terminal +B voltage of the transmission control ECU is 9.3 V or less for 1 second or more.

The other areas to check are:

• HEV fuse
• IGCT relay
• Wire harness or connector

When checking the HEV* fuse, use an ohmmeter to check for continuity, specifically:

1. Remove the (20A) HEV fuse from the engine room relay block.
2. Measure the resistance of the fuse.

Standard resistance: Below 1 Ω – is considered a good result. If it is 1 Ω or above: inspect for short in all components connected to fuse and repair or replace them if needed, and replace the fuse



I hope that helps.



* No I don't know for what this is an acronym, but it protects the IGCT relay first and then the B+ of the Transmission Control ECU and, I believe, the HV Control ECU.



PS: One of the history codes (B1271) indicates your CM (combination meter) is intermittently failing. You can use advanced search to search the Prius Gen 2 forums (by clicking on the "More..." button in the search dialogue at the top of every page.

Note, this is a separate problem and unrelated to the discussion above. Fix the above problem, then see if the intermittent CM goes away too. You know, you just might be lucky.

There is also the combination meter repair - DIY post pinned to the top of this forum (skip to page 10 ff after reading the first couple of posts) and there is also this one: Combination Meters that stop at 299,999 miles, who are affected and what you can do about it. which doesn't affect your 2007 Gen 2, but has other info in regards to fixing the CM and contact details for Texas Hybrid Batteries.