Chasing Code issues 2015 Tahoe (P0430 and Tighten Gas Cap)

[bonedog]

I am intermittently getting the codes/messages noted above. I've already replaced the O2 sensor on the right side as noted (I know there's two of them), but I'm wondering if anyone's had experience with both of these popping up on your vehicle and a solution for it? Gas cap is always tight and it doesn't matter where the gas was bought from, how full the tank is, etc.

Never seems to effect the way it's running, idling, etc.

If there's a test that can be done, please post a link/details to it. My nephew is a tech for Mercedes and can do what I need him to but I need to "feed him" the info (don't get me started...).

Thank you!

 

[Tahoe14]

You may need to replace the gas cap if you have not done so.

 

[Rygrego]

You may need to replace the gas cap if you have not done so.

Why? That has nothing to do with this code. A evap code would point to a gas cap.

 

[Fless]

Why? That has nothing to do with this code. A evap code would point to a gas cap.

Multiple codes. Read the title.

 

[Rygrego]

Multiple codes. Read the title.

Title reads :

I read one code from title,​

Chasing Code issues 2015 Tahoe (P0430 and Tighten Gas Cap). No evap codes.​

 

[Fless]

Yes, well, "Tighten Gas Cap" isn't a code, you're right about that. One could call it a description of an evap code, no?

 

[Rygrego]

Yes, well, "Tighten Gas Cap" isn't a code, you're right about that. One could call it a description of an evap code, no?

Not trying to be a smart ass , but the only reason to check a gas cap would be for an evap code, it would not change the code mentioned. There is no evap code present. The code mentioned is for a catalytic system below efficiency threshold. The picture of the scan tool states one code and says nothing about a gas cap. I get the impression the author said he tightened the gas cap because that is what everyone does when a check engine light comes on just in case. Replacing the cap would be a waste of money in the absence of an evap leak code.

 

[swathdiver]

I am intermittently getting the codes/messages noted above. I've already replaced the O2 sensor on the right side as noted (I know there's two of them), but I'm wondering if anyone's had experience with both of these popping up on your vehicle and a solution for it? Gas cap is always tight and it doesn't matter where the gas was bought from, how full the tank is, etc.

Never seems to effect the way it's running, idling, etc.

If there's a test that can be done, please post a link/details to it. My nephew is a tech for Mercedes and can do what I need him to but I need to "feed him" the info (don't get me started...).

Thank you!

P0430 is for a bad cat on the passenger side. It does not mean you have a bad O2 sensor, lifter, bad taste in music, just a bad cat.

I would ask myself, why did the cat go bad?

From the previous generation's shop manual:


Circuit/System Testing

1. Inspect for the following conditions, which may cause a catalytic converter to degrade:

• An engine misfire
• High engine oil or high coolant consumption
• Retarded spark timing
• A weak or poor spark
• A lean fuel mixture
• A rich fuel mixture
• A damaged oxygen sensor or wiring harness
• The catalyst test may abort if the vehicle falls outside the conditions for running the DTC.
• A catalyst may be temporarily degraded if a fuel with high sulfur content has been used. Drive the vehicle at highway speeds for 10 minutes and retest the converter.

1. Inspect the catalytic converter for the following conditions:

• Dents
• A severe discoloration caused by excessive temperatures
• Road damage
• An internal rattle caused by damaged catalyst substrate
• Restrictions
• If a condition is found, replace the catalytic converter.

1. Inspect the exhaust system for the following conditions:

• Leaks
• Physical damage
• Loose or missing hardware
• Restrictions
• If a condition is found, repair the exhaust system.

1. Inspect the post catalyst HO2S for the following conditions:

• HO2S not at the correct torque.
• Damage
• If a condition is found, replace the post catalyst HO2S as necessary.

1. If all physical conditions test normal, test or replace the catalytic converter.

Repair Instructions

Note: A new converter with less than 100 miles on it may set DTC P0420 or P0430 due to out-gassing of the internal matting. Operating the vehicle at highway speeds for approximately 1 hour may correct the condition.

 

[Fless]

Not trying to be a smart ass , but the only reason to check a gas cap would be for an evap code, it would not change the code mentioned. There is no evap code present. The code mentioned is for a catalytic system below efficiency threshold. The picture of the scan tool states one code and says nothing about a gas cap. I get the impression the author said he tightened the gas cap because that is what everyone does when a check engine light comes on just in case. Replacing the cap would be a waste of money in the absence of an evap leak code.

Not trying to be a jerk, either, but it seems like you're picking nits. The OP stated he has multiple codes, he just didn't list them all. He showed one code (of three in the scanner) and wrote another code's description. @Tahoe14 appears to have responding to the code that was described. It's "bigger picture" stuff. Yes, I'm quite done now.

 

[bonedog]

Thanks all. For what it's worth, there's only 1 code that's thrown and the scanner has 3 pages that show/describe the code. The only code is P0430. The DIC will sometimes tell me to tighten gas cap, but there's no code that gets stored. But, for $6, I replaced the gas cap. Now...everyone can take that one off the potential culprit list.
The Check Engine Light hasn't been on for a week or so. It will come on, stay on for a week or so then it will randomly go off. I'm not adding gas, running low on gas, etc. when it happens so there's no pattern I can draw from that.

I do have 148k miles on the Tahoe and it started doing this at about 110k miles. I'd truly hate to think that my cat is, in fact, bad...but that's why I'm here asking the backyard mechanics.