LexBrett

After my engine rebuild by the criminal mechanic, I'm still fixing random problems. Still have a couple error codes, p0125 and p0430. With the p0125 I'm stumped! The ECT sensor I just replaced, and I replaced the entire radiator so I know the coolant level is optimal. The thermostat appears to be working and is not stuck open, which I have also cross referenced with my engine coolant temp on my dash command app. What else could cause the p0125??

I also have a p0430 code which is catalyst inefficiency on the post cat drivers side. I JUST replaced those sensors after my header install which made the previous instance of the p0430 go away. Maybe the douche mechanic broke the sensor?? It seems to be reading voltage on Dash Command App. Checked for a exhaust leak by running seafoam through pcv valve and looking for white smoke but I didn't see a leak. I'm also planning to check bolts on cats, maybe a leak is actually there and I can't see it? Anyone have any other ideas on the p0430?? Guess I will be forced to buy another 02 sensor if I can't find leaks and O2 sensor is properly seated..

Lastly could the p0125 and p0430 be RELATED somehow?????

FlopTop04

The P0430 could be from a few things. A leak, a bad sensor or a bad cat are the most common. The plot thickens with the recent headers and engine swap. Check that bolts are tight with no leaks around the gaskets. Verify the sensors' harness connection and the wires for damage. TechStream will give good info on the sensors heater and ECM input variations.

When I had that code at 93,000 miles on a completely stock engine, it was the cat. Big money $$$ if Lexus did the repair. I got a quality after-market cat and did the install myself for $400.

LexBrett

Well maybe this will be an excuse to get the magnaflow cats I have been wanting:-) the cats were fine before the engine rebuild though. I feel it has to be either a broken O2 sensor, an unseated sensor, or a leak. Any thoughts on my strange P0125 code?

JohnnyCake

The guy in this thread got BOTH those codes after replacing his valve cover gasket, which required him to also pull a coolant line. Unfortunately, he never circled back to close the loop and indicate what fixed the problem, but the 02 sensor was also suggested as a possible culprit. Better that than the catalyst.

Kinda basic, but RU sure you have the correct thermostat.

LexBrett

Good question about the thermostat. The bad mechanic claimed to have changed the thermostat. It does seem to be functioning though and getting to the correct temperature. My understanding of p0125 was that it would come on when the thermostat is stuck open, thereby not allowing engine to get to running tempts. But in my case the temp are good. I also checked on my dashcommand app, which reads the signal from the ECT sensors.

Yeah I saw that thread with the other guy that had the same pair of coded. Wish he could have closed the look to help us out!!

LexBrett

After reading more closely I saw that that guy with the same pair of codes suggested there was a vacuum leak somewhere. Will check all of my connections!! Today I was doing my plugs and everything seemed in tact but I did notice that some of the vacuum lines were not properly hooked up to my cold air intake... This is very puzzling..

LexBrett

I'm going to use my dashcommand app to record diagnostics and report back.

I plan to record O2 sensor voltage, ECT temps, etc. For example, I think I saw a constant temp for my coolant and makes me think that the sensor is not reading indicated a short or it is not seated properly.

Any other diagnostics I should record to assist with the diagnosis??

Bgw70

Lex, you are doing the correct diagnosis. If your app has the ability to show the O2 sensors on a graph, it might be more helpful. And checking the temp sensor is a great idea.
I have read that the P0125 can certainly be caused by a faulty temp sensor.

Helogadget

Lex, here is my .02 on this issue. I did a little reading up and PO125 says the ECU is not reading a sufficient coolant temp rise to enter closed-loop for the fuel system. If it doesn't enter closed-loop, then I believe this may be causing your PO430. I would highly suspect the coolant temp sensor. First check the connection and the wiring harness before considering replacing the sensor.

You should be able to read your coolant temp off your Dash Commander. The temp should start off as ambient and then go to around 180-190 degrees once up to operating temp.

I would bet that once your got the coolant temp issue resolved the PO430 will go away.

LexBrett

Checked my vacuum lines last night and there was a BIG leak. Going to zip tie everything down tonight (will later reinforce properly). I wonder if the leak was throwing the code. Just did my Dash Command recording this morning, and and I am going to create a pivot table and I will post the results as soon as I have a chance!

LexBrett

Looks like the ECT sensor is working fine..no?



Reading was taken for about a 15 minute drive. Temp gets to just under 200 degrees, which is normal. ECT sensor seems to be functioning..

Helogadget

That looks normal. No worries there for sure.

LexBrett

Thanks! Will do the O2 sensors next

LexBrett

Here is the analysis of my O2 sensors. Just realized that these are only for my precat sensors, which is irrelevant for my p0430 code. My dashcommand app did not have the other PID activated for post cat sensors, which I will do tomorrow..

LexBrett