CHECK ENGINE LIGHT STILL ON AFTER SPENDING OVER $1,000

My 03 4.7 V8 Tundra, with 99,000 miles, still has ck engine light on after spending $665.55 and another $314.39 at the same repair shop. I chose this shop after reading many excellent reviews.

The first repair included replacing Upper Plenum gasket and the lower intake manifold gaskets.
The shop determined that there was a vacuum leak. The codes they encountered were P307 cyl 7 misfire, P0051-O2 control circuit low bank 2 sensor 1, P0154-O2 Circuit no activity Bank 2 sensor 1, and P0430 catalyst system efficiency low bank 2.

They initially replaced ignition coils on #5 and #7 but removed them when the engine still idled rough. They then did a smoke test and found the vacum leaks.

When I left the shop, I was pleased as the check engine light was off and the truck ran perfectly. After driving 10 miles the check engine kight came back on!

On return to the shop, they pulled a P0430 code and subsequently replaced the bank 2 upstream O2 sensor. I paid my second bill of $314.39 and drove away with no check engine light on.

The next day after driving another 10 miles the light came back on! I traded gas caps with my son who has an 04 tundra. Light still on.

Before going back there, I would like to know if anyone out there has any idea of what my problem is? Truck runs perfect after 150 miles of combined driving. After some reading, I don't think the sensor needed replacing. Light is still on!

 

Curious, what's the latest code? Any auto parts store (Auto Zone, Advance Auto, O'reilly etc) can pull diagnostic codes for you. Knowing what the latest code is would help give you the best possible advice. Sounds like you or your shop is playing whack-a-mole trying to nail down this problem, potentially throwing parts at things based on codes, but failing to do necessary diagnostics which would confirm 100% you're applying the right part for the condition.

Note: CEL doesn't always appear nor go away immediately on modern vehicles. This is especially true with emissions-related repairs such as gas cap, EVAP, vacuum etc. Many ECU require you to meet a few different driving thresholds before it recognizes, "Hey, I'm OK!" and clears out. Granted, you should be able to CLEAR codes and not have them come back until that same testing cycle has completed, which sometimes means a delayed code days or weeks later depending on how you drive. So, in your gas cap example, it could take hours, days or weeks to clear the CEL on its own *if* improper fuel tank pressure was the problem.

 

Not sure it relates but my O2 sensors kept trippin CEL lights, turned out to be a cat on its way out. Replaced the cat on the side I kept getting issues with o2 sensors, and it went away. Just throwing that out there.

 

Shifty, thanks for your quick response.
The code is P0430 Catalyst system efficiency low bank 2

 

I would have tried the downstream sensor for that code. Before you go back and spend another $350 are you comfortable changing a sensor yourself? Its really easy on these trucks, you don't even need to jack the truck up. If you can change a light bulb you can change the sensor.

Watch a few youtube videos. See if you're comfortable. You can get the sensor you need at any website like rockauto or carparts.com but get a denso brand sensor. These trucks are a bit picky and don't seem to like Bosch sensors. It will cost you in the ballpark of $100 and you can do it.

Sounds like this shop is kind of making quick guesses and hoping things work. Not uncommon unfortunately. They can test things like coil packs or O2 sensors if they know how and avoid throwing parts at the problem. They may have cured a few problems within your first visit from the sound of things, if all you have left is the 430 code.

 

Asking another potentially pertinent question: How many miles are on your truck?

This ^^

I also agree, could be bad cat, which will set you back more than you've already accumulated in bills. While I've always felt the products are gimmicky, some folks swear by OXICAT, Solder-It CAT-1, and Cataclean to help dissolve and burn off buildup in your cats. It is a life-limited product though, cats across all manufacturers typically last 100k-200k miles depending on maintenance. If you use shit gas or allow the engine to burn inefficiently for any extended period of time, you can expect to be on the lower end of that spectrum. Not sure if either case applies for you.

 

Try the downstream O2 before you worry about the cat. I've seen the 430 code clear from upstream sensor before but its usually the downstream in my experience. Both have to work properly, it's possible both were bad.

 

I fought a P0430 problem for about a year. Assuming your cat is not plugged, I confirmed mine was not when I replaced the flange gaskets, then you might save some money if you can find a willing mechanic to do a fouler install. Otherwise you can read some threads on Walker vs Magnaflow vs universal vs OEM cats and have a new one installed. I've ranted in other threads but will do so again. I think it's complete BS that when cat efficiency falls from 100% to 96% we as owners are required to spend upwards of $1,500 just to gain 4% of efficiency. Good luck.

https://www.tundras.com/threads/bad-cat-w-02-sensor-obd-data.95762/#post-2427929

 

I have a 2001 w 196k miles and the check engine light has been on for about 100 miles. I think it is some type of oxygen sensor but it runs fine.

 

Since it's just the rear, you could always just use a simulator circuit to test it. Of course, leaving it in would resolve the issue as well.

 

How did you confirm you cat wasn't plugged?

Back story, I bought my 01 Sequoia with a cylinder misfire, replaced the coil and all was good there, but I've got the cat code and the exhaust does smell a little like rotten eggs. I've tried monitoring my O2 sensors with torque pro, but I can't tell what I'm looking at.

 

Try cleaning the throttle body and MAF. Also, I found that one of my CATs was loose and leaking at the gasket (or rather where the gasket used to be). New gasket and SS nuts solved the problem for ~ $10.

 

In my 1997 T100 the check-engine-light has been on for 9 years and 80,000 miles. It just keeps going. And going. And going. Using gas mileage as one gauge of performance it runs better than the day it was new off the lot.

The most amazing part is that that liiiiiiiiiiiitle light bulb that illuminates the CEL is still rocking on.

 

What makes you think that?

 

My mechanic pal mentioned that’s what it might be.

 

I've given up chasing my CEL Code. Has a P0136, I've replaced the upper and lower o2 Sensors and the cats and it comes right back on. CEL Forever gang where you at?

 

You might want to try a couple of tanks of premium gas.

 

Might need to take out a mortgage for 50 gallons of premium.

 

*stares at supercharger*
You guys run regular?
*Contemplates if the knock is worth it*
I could save money on gas which leads to more money for mods.....
*smiles*

 

I was getting a bank 1 catalyst system CEL and found a leak on my exhaust gasket post cat before the final O2 sensor. changed the $5 gasket and hasn't been back.

Found it by starting the truck on a cold day and putting my hand over the tailpipe and watched the steam come out from the bad gasket.

 

Thank you for sharing. I think I have resolved my cel. I discivered that my down stream O2 was not tight. I tightened it with the special scoket, disconnected the battery for 24 hours, and have now driven 140 miles with the cel off!

It was my fault that it was loose. The downstream O2 sensor from the factory was not threaded so I didn't realize that the replacement was when I installed it. As you know, the down stream O2 on the 03 Tundra is attached to the pipe by bolting the bracket to which it is attached to the exhaust pipe.