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Discussion Starter #1
Hello All,

I have been having this error code pop on me starting about 3 months ago. When it first came up I cleared it and it went away. Then about a month ago it came back and I cleared it and it went away. Then about a week ago it came back and now it comes back roughly every 60 miles. I had both intake manifolds replaced at the beginning of the year. I assume they did o2 sensors when they replaced the manifold/cat. The manifolds are oem as I live in California and nothing but the most expensive will do. I cleaned the MAF sensor and replaced the air filter last night. My titan is an 06 with roughly 200k miles on it. I am a beginning wrencher but happy to learn and would love to be a full time DIYer.
Thoughts?
Thanks
Aaron
 

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That's a lean indication, so check for air leaks on the intake and especially exhaust system leaks, possibly leaking exhaust manifold gasket. I assume you mean exhaust manifolds were replaced... if the manifold bolts weren't retorqued after some miles (usually 100 or so), then they could have loosened up a bit (suggest taking it back to where you had the manifolds installed and have them check for leaks - and verify O2 sensors were replaced).

Otherwise, could be faulty fuel injector or even low fuel pressure (a good shop can check that, too).

I'm betting exhaust system leak, since you just had that worked on.

Good luck!
 

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Discussion Starter #4
Thank you all very much. Is it the exhaust manifolds that crack? I thought it was intake but like I said...I am fairly new to all this. I cleaned the MAF sensor, replaced the air filter. Sounds like I need to take it back to the shop and have them look at it. If it's related to their previous repair they will take care of it. I'm only hesitant because here (San Diego) they charge you 100 dollars to do a diagnostic. You can get them to waive it if you leave it with them for repairs but I don't want to pay 100 dollars for something that I am not going to leave with them to fix.
How would I check for an exhaust leak, or low fuel pressure? I have an OBDII.
Thanks everyone!
Aaron
 

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Old O2 sensors cause rich conditions in general. They are usually the cause of plugged cats. Consider also, that any air leaks before the Cats will also trick the O2 sensors and cause them to demand the ECU manage the injectors to go rich.

If you're lean, it's probably an issue elsewhere.

Here's a list of likely suspect areas:
An intake manifold leak.
A weak fuel pump.
A clogged fuel filter.
A faulty powertrain control module.
A vacuum leak.
Faulty injector(s)
A faulty mass air flow sensor.
 

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Discussion Starter #7
Is there a way to test the MAF sensor and the injectors? The truck runs the same way it always has. The intake manifolds and o2 sensors were replaced earlier this year (january and then april.)
 

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I was suspicious of the MAF when you said you cleaned it, but you didn't say with what. The only product that is safe, is actually called MAF cleaner. Brakeclean, carb and choke and other cleaners contaminate the materials used in the MAF. Also, never touch the wires of the MAF with qtip or other items.

So, that said.....You need a multimeter with DC setting...nothing fancy necessary. Also, you need wire piercing probes or two paper clips or two really thin finishing nails. Here's the 'how to' ....

As far as your O2's....hopefully they are OEM. If not, that could be your problem. Some places use 'universal' sensors and splice the wires....a source of failure. Even if OEM,, check to make sure the connections are complete. It's always a good practice to use dielectric grease in weather tites also.....sort of a suspender and belt approach. Check that the shop didn't run the wires too close to hot parts...I've seen them melted to the exhaust...which is an instant fail.

With the miles you have on your truck, check the vacuum hoses for cracks and loose fit. PCV hoses are notorious for cracking.

Testing of injectors is usually not the sort of thing for DIY because you can only tell if they are operating or not, but you can't tell how well. That's done on a bench with special equipment. Basically you need an automotive stethoscope and you put the probe at the base of each injector while the engine is running at idle and you listen to the clicking. No click is an obvious failure. Ideally, they will all sound the same level of loudness....with your miles, I'd suspect that won't be the case. Next you need the multimeter and you check each injector's ohm reading. They should be within 10-15 OHMs. Check the service manual and get the exact, but if I recall, the sweet spot is 12 OHMs. Out of range and it's shot. The performance of a worn injector cannot be fixed with anything you pour in a gas tank so save your money. The performance aspect, the how well they are working has to done at a shop that has the equipment to check the patterns of spray and then rebuild as needed. There are plenty of places that do this all over the internet.

Check the work done on the intake by removing the shroud and while the engine is running and at operating temp, follow these instructions:
 

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Discussion Starter #9
Thank you so much! I will be doing this this weekend and getting back to you.
As for the MAF...I did use MAF cleaner. At least I got that one right!
 

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Just wanted to update everyone.....
Took the truck to the same shop that swapped out my manifolds and replaced my 02 sensors. They think it might be the 02 sensor and are going to replace it foc since they put the last one in so recently (april). The error is odd though as it will stay off for up to a week after I clear it and then come back suddenly and come back every 10-50 miles and then go off again (never on it's own...always when it's cleared.)
I will keep you updated in terms of what happens after the 02 sensor is replaced.
Also....someone suggested a new gas cap? Wouldn't that have given me a different code if it was the gas cap?
Aaron
 

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Aaron, I'm running into this issue now. What was your final outcome? I know it's been three years, but do you remember? Cheers!
 
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