2015 Yukon 5.3 p0430 code help!
- Thread starter Edward85
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You should ask your mechanic what kind of wiring issues would cause that code.
What are the downstream O2 sensors doing, have you graphed those? Especially Bank 2.
What do the long term fuel trims look like?
What are the downstream O2 sensors doing, have you graphed those? Especially Bank 2.
What do the long term fuel trims look like?
The bank 2 graph is in the picture he said there are 2 fuses under the hood that control the 02 sensors to double check those and he also said to buy gm o2 as the aftermarket ones don’t work on these suv. I will try and get a fuel trim chart.
Yeah, sorry, I missed those downstream lines. I don't see anything wrong with either readings, upstream or down. It would be interesting to see if the fuel trims are good, or excessive one way or the other. The direct injection engines do have issues with the high pressure fuel pumps leaking into the combustion chambers.
The link below is for a 2013 system; I don't have any info for a 2015. However, I would bet that the strategy to check the cat is the same. Take a look at it to see if you can run some tests.
The link below is for a 2013 system; I don't have any info for a 2015. However, I would bet that the strategy to check the cat is the same. Take a look at it to see if you can run some tests.
P0430 — 2013 GMC Yukon 4WD V8-5.3L Service Manual | Operation CHARM
Detailed repair manual for the 2013 GMC Yukon 4WD V8-5.3L.
charm.li
West 1
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The after cat O2 sensors look perfect. Reading steady above .700. No issue there.
The before Cat 02 sensors are both adjusting but the Bank 2 Sensor 1 RED line looks lazy, it is reacting slower than the Green line.
Bank 2 Sensor 1 is before cat that sensor is lazy and should be replaced.
Before cat O2 sensors are always jumping from .150 to .800 in normal operation. When they jump slowly the sensor is reacting slow which lets your Fuel trim adjustments react slowly. Just study how the Red curve is much wider than the Green curve. Green is reacting faster as it should.
Your picture is only a couple seconds of a reading so watching for a longer period of time may show results vary but that is what I read in your picture. Keep us posted on your repair.
I have had good luck with Bosch, Denso or Standard Ignition O2 sensors. Keep in mind GM does not make them, they rebox and sell parts in AC Delco boxes. Granted GM usually chooses a good supplier to put in the box but you can do that also.
The before Cat 02 sensors are both adjusting but the Bank 2 Sensor 1 RED line looks lazy, it is reacting slower than the Green line.
Bank 2 Sensor 1 is before cat that sensor is lazy and should be replaced.
Before cat O2 sensors are always jumping from .150 to .800 in normal operation. When they jump slowly the sensor is reacting slow which lets your Fuel trim adjustments react slowly. Just study how the Red curve is much wider than the Green curve. Green is reacting faster as it should.
Your picture is only a couple seconds of a reading so watching for a longer period of time may show results vary but that is what I read in your picture. Keep us posted on your repair.
I have had good luck with Bosch, Denso or Standard Ignition O2 sensors. Keep in mind GM does not make them, they rebox and sell parts in AC Delco boxes. Granted GM usually chooses a good supplier to put in the box but you can do that also.
You could swap the front (upstream) O2 sensors and re-graph to see if the reaction delay is a sensor issue or something going on with that bank.
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swathdiver
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Bank 2 is showing less stability than Bank 1 on the downstream sensor. Bank 2s upstream sensor appears to be giving a lazy reading like @West 1 suggest.
Any work down on the exhaust manifolds, Y-Pipe or plugs and wires lately?
Generally, a P0430 code only throws a false positive when there is a massive exhaust leak on that side, like a loose connection between the manifold and Y-Pipe or the O2 sensors are not screwed down all the way, etc. Bad O2 sensors have their own codes.
Have you cleared the code and noted how long it takes to come back?
could be a bad cat, but you could gamble and replace both passenger side 02 sensors and roll the dice, cheaper than a replacement cat.
and if the cat is bad then at least you already have new sensors
the denso's when available will work as that is what would come in a ac delco box anyway
your "mechanic" is wrong on both counts
and if the cat is bad then at least you already have new sensors
the denso's when available will work as that is what would come in a ac delco box anyway
your "mechanic" is wrong on both counts
West 1
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With both sensor 2 after cat O2 sensors reading perfectly it tells you there is no extra O2 in the exhaust system. If you read a car with an O2 leak the sensor 2 readings will be very low. Maybe ..150 to .400 rather than .700+. If the cat is bad the rear sensor 2 will read almost identical to the front sensor 1 O2 sensors. Jumping up and down from .150 to .800 constantly almost an exact pattern to the front O2 sensors.
I have tested a failing cat where it would read perfectly after a hot drive but soon once at idle the Sensor 2 reading would start to mirror the sensor 1 reading.
The only way you get a near straight line above .700 reading at the after cat o2 sensor is if the Cat is working because it has cleaned the exhaust.
Dirty exhaust or extra 02 at the after cat sensor will read low. Below .400
The fact you see good readings at both Sensor 1 locations and both sensor 2 locations says the wire are all working at the time of that test and that is all we have to look at.
If you want to test if the O2 sensors are reacting as they should, a very simple test is to start pumping the brake pedal as the engine is at idle and you are reading the O2 sensors with a scan tool.
As you pump the brake it changes the fuel mix by creating brief vacuum disruption, you want to be quick, on the brake off the brake, do this for about 30 seconds. The sensors will quickly read the change and once you stop pumping the brakes they quickly go back to normal.
What threw his code may be an intermittent issue because the sensors are reading perfectly in his post picture.
I have tested a failing cat where it would read perfectly after a hot drive but soon once at idle the Sensor 2 reading would start to mirror the sensor 1 reading.
The only way you get a near straight line above .700 reading at the after cat o2 sensor is if the Cat is working because it has cleaned the exhaust.
Dirty exhaust or extra 02 at the after cat sensor will read low. Below .400
The fact you see good readings at both Sensor 1 locations and both sensor 2 locations says the wire are all working at the time of that test and that is all we have to look at.
If you want to test if the O2 sensors are reacting as they should, a very simple test is to start pumping the brake pedal as the engine is at idle and you are reading the O2 sensors with a scan tool.
As you pump the brake it changes the fuel mix by creating brief vacuum disruption, you want to be quick, on the brake off the brake, do this for about 30 seconds. The sensors will quickly read the change and once you stop pumping the brakes they quickly go back to normal.
What threw his code may be an intermittent issue because the sensors are reading perfectly in his post picture.
