2014 SILVERADO P0430 CODE NIGHTMARE

[Chad Earnhardt]

Hello Folks,

new to this group.

I have a 2014 silverado 4x4 5.3 V8 crew cab short bed 180,000 miles

About 4 months ago i started getting several check engine codes related to 02 sensors and cats.

i had a shop replace all o2 sensors one at a time until all lights codes were resolved. 40 miles later i started getting the P0430 code for catalyst below efficiency threshold bank 2 side 2

The shop ran several diagnostics including checking MAF and MAP sensors. replaced the Map sensor and cleaned the MAF, checked for exhaust leaks (none found) checked injectors (correct Pressure) checked 02 sensor readings (readings were ok per the diagnostic computer), ended up replacing the cat converter on passenger side. reset computer, drove it in the recommended break in cycle per tech bulletins. withing 40 miles the same 430 code was back on. after over $1500 in expenses already i took it to another shop. again all the above diagnostics were performed. we changed  out both 02  sensors on passenger side with a higher quality sensors. light still came back on within 5 miles. we decided with no other good options that we should change out the new cats (300 miles on them by now) with magnaflow cats to rule out bad parts. reset light drove it again the recommended cycle. within 20 miles same dang code was back on. i am also eperiencing a code for low oil pressure P0521 i think. we have not fixed this yet. it was determined that it is a bad sensor for that as well. both highly skilled mechanics are out of options. what are we missing and could that low oil pressure sensor somehow be affecting this exhaust code. Help i am in over $2500 with no solution yet.

[CamGTP]

Usually only the OEM cats are good enough for the stock calibrations. Aftermarket cats like those magnaflows don't have the same build quality and amount of metals inside them to keep things happy.

 

A cheap option to try is spacing the rear o2 sensor out of the exhaust a little bit to see if that stops the code. They are usually called spark plug non-foulers but they have the same thread pitch as a o2 sensor, with those it can space the o2 sensor out far enough to maybe stop the code from coming up. It's a pretty common thing to try and many aftermarket headers with cats will do this already, though I don't see them on the GM LS/LT engine stuff. You can google/youtube this trick to try.

[swathdiver]

My Magnaflow cats have been on the truck for 50K miles without issue.

 

If the OP has replaced all these parts and still getting a code, either something is wrong with the engine on that side, or the ECM is bad.  These trucks don't take kindly to aftermarket parts, use GM OE or ACDelco Professional/Gold only.

[WillG]

Have you found any resolve to this issue? I have a 2016 gmc Yukon Denali 6.2 with new cylinder heads / lifters and catalytic converters. Replaced all of the above because of a cracked cylinder head that failed the cat on bank 2. Everything used is oe besides the cats. They are a walker brand, I’ve had some success with them in the past on 5.3 trucks.

[TheFierro20]

Have you resolved this issue? I’ve been fighting the same code for a year now with no luck and I’ve done the same.

[dieselz]

To address the persistent P0430 code on your 2014 Silverado, consider checking for exhaust restrictions beyond the catalytic converter, inspecting O2 sensor wiring for damage, and possibly updating/reprogramming the ECU. Also, revisit the possibility of a small exhaust manifold or gasket leak on the passenger side. Fixing the low oil pressure sensor (P0521) may not directly resolve the P0430 code, but it's worth addressing to rule out any related issues.