P0230 and now P0175 codes '09 5.3 Tahoe

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PatDTN

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Yay! I've been searching for something else to spend money on. :boxed:

I've gotten the P0230 code for a while and cleared it several times. It comes back fairly quickly when I start driving. This morning after a couple of tries getting codes I got the P0175 in addition. Could that be related to turning the key to run and not starting it several times while fiddling with my reader?

Screenshot_20200724-085150_ChevroSys-Free.jpg

The latest code has me wondering if I have a bad relay. I tried searching this section of the forum but don't see either of these codes.

Thoughts and suggestions welcome.
 

OR VietVet

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These two codes could be related or two completely separate problems.

Related to code P0230:

P0230 code definition
Fuel Pump Primary Circuit Malfunction

What the P0230 code means
P0230 is a generic OBD-II code which indicates that the fuel pump primary circuit has a malfunction of the vehicle power to the fuel pump when it is commanded on or off

What causes the P0230 code?
  • The engine control module (ECM) detects the primary fuel pump circuit voltage as below specifications from the fuel pump relay to the ECM

  • The fuel pump relay main power supply could be low from a blown fuel pump fuse or fusible link, or from a shorted fuel pump or circuit
What are the symptoms of the P0230 code?
  • The Check Engine Light will be illuminated

  • The fuel pump may become inoperative if the fuel pump and relay is bad

  • The engine may not start from a lack of fuel pump operation
How does a mechanic diagnose the P0230 code?
  • Scans codes and documents the freeze frame data in order to verify the problem

  • Clears the DTC codes to verify whether the concern comes back

  • Checks the fuel pump fuse or fusible link to see if it is blown

  • Tests voltage to the fuel pump relay primary circuit to be battery voltage

  • Tests fuel pump relay primary circuit resistance for an open circuit
Common mistakes when diagnosing the P0230 code
Follow these simple guidelines to prevent misdiagnosis:

  • Verify that the battery voltage is within specifications and connections are good

  • Check the electrical connections at the fuel pump relay for overheating from a fuel pump drawing too much power and overheating the circuit
How serious is the P0230 code?
  • The fuel pump primary circuit powers the fuel pump relay and can cause a no start

  • A low battery voltage can trigger the code if the voltage falls below a specified level

  • The fuel pump may be drawing too much power and cause the low voltage condition
What repairs can fix the P0230 code?
Additional comments for consideration regarding the P0230 code
Code P0230 is triggered by low voltage in the main power circuit of the fuel pump relay. The ECM monitors this voltage to see if it falls below a specified voltage.

If codes P0231 or P0232 are present, then follow the pinpoint tests for these codes first to narrow down the failure on the secondary side of the fuel pump circuit.


P0175 info:

P0175 code definition
P0175 System Too Rich (Bank 2)

What the P0175 code means
P0175 indicates that the Engine Control Module (ECM) detects too much fuel and not enough oxygen in the air fuel ratio (AFR). This code will set when the ECM can not compensate for the amount of air or fuel required to return the air fuel ratio back to the set parameters.

For gasoline powered engines, the most fuel efficient and cost efficient air fuel ratio is 14.7:1, or 14.7 parts air and 1 part fuel. This ratio also creates the maximum amount of power during the combustion process.

The combustion process is very simple yet fragile. In most vehicles, there are four to eight combustion chambers within the engine. Air, gasoline, and spark are all delivered to the combustion chambers to create an “explosion” (better known as combustion). The spark is delivered to each combustion chamber a nanosecond after the air and fuel reaches the chamber to ignite it. There is a piston in each combustion chamber; each piston is forced down by the combustion at a rapid rate, and at different times.

The difference in the timing of each piston is determined by the air fuel ratio and the timing of the engine. Once the piston is down, it must return to the up position in time for its next combustion process. The piston is forced back up little by little each time one of the other cylinders undergoes its own combustion process because they are all connected to a rotating assembly known as the crankshaft. It’s almost like a juggling effect; at any given time, one piston is on its way up, while another one is at its peak, and another piston is on its way down.

If something in this process goes out of sequence, internal engine components will work harder and work against each other, or the engine may even not run at all. In the case of code P0175, there will likely be higher gas consumption, as the ECM has detected that there is too much fuel being used.

What causes the P0175 code?
  • A clogged, stuck, or leaking fuel injector
  • Faulty fuel regulator
  • Dirty or faulty mass air flow sensor
  • Faulty coolant temperature sensor
  • Faulty thermostat
  • ECM needs reprogramming
  • Dirty or faulty oxygen sensor
  • Vacuum leak
  • Fuel delivery problem
  • Incorrect fuel pressure
What are the symptoms of the P0175 code?
  • Increased fuel consumption
  • Soot or black residue from exhaust
  • Check Engine Light illumination
  • Strong exhaust odors
How does a mechanic diagnose the P0175 code?
  • Checks the fuel pressure

  • Inspects the fuel injectors for restrictions

  • Checks fuel injector pulse

  • Examines the fuel lines for pinches or cracks

  • Inspects all vacuum lines for cracks and deterioration

  • Inspects the oxygen sensors

  • Uses a scan tool to read the engine temperature, then compares the findings to an infrared thermometer
Common mistakes when diagnosing the P0175 code?
  • Not checking the temperature of the engine with a scan tool and comparing it to a thermometer

  • Deeming a component bad without verifying through testing
How serious is the P0175 code?
  • A system that is running too rich will force the catalytic convertor to filter out more pollutants, which will shorten the lifespan of the catalytic convertor

  • The resulting increased gas consumption could be very expensive

  • Improper air fuel ratio causes the engine to work harder, which will shorten the lifespan of the engine

  • The engine will create increased levels of harmful pollutants
What repairs can fix the P0175 code?
Additional comments for consideration regarding the P0175 code
I strongly suggest verifying that the cooling system of the vehicle is working correctly. If the vehicle is running abnormally cool, the engine will always run in a rich condition. This is because the ECM is designed to run at a rich rate when cold to help warm the engine up faster. If the coolant temperature sensor is faulty or the thermostat is stuck open, the vehicle may never reach a warm temperature, which will cause it to always run in a rich condition.
 
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PatDTN

PatDTN

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D'Oh! After looking over that response I realize I'm backwards on which one I've had and which one is new. The P0175 is the one that's been around and been reset numerous times. The P0230 is new. Sorry. Thanks for the response.

I've just found there is a 2015 GM recall for the FPCM. https://static.nhtsa.gov/odi/rcl/2014/RCRIT-14V614-0055.pdf Actually the title is "Chassis Electronic Control Module Internal Contamination"
 

OR VietVet

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Yes, get that recall done and clear codes and see what may or may not come back.
 
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PatDTN

PatDTN

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Yes, get that recall done and clear codes and see what may or may not come back.

I called the dealer I've used since they have my VIN already in their system. Apparently this recall doesn't apply to my Tahoe. The recall does state it doesn't apply across the board.
 
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PatDTN

PatDTN

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My follow up. I decided to replace my oxygen sensors. With 200k miles and rust and some other issues I cheaper out and bought some crappy ones on Amazon. Things went crazy and worse.

Using my reader I found one was completely inoperable and the others were just sending a random stream of bad information. I bought a set of ACDelco oxygen sensors and swapped those in.

That fixed the crazy readings but then I got that one of my catalytic converters was compromised. I've been running it and it seems to have burned itself clean and the error stays cleared now.

Moral of the story is don't cheap out. Amazon refunded the money on the cheap sensors. Now I'm worried because I had bought the same brand front bearing assembly.
 

OR VietVet

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Good follow up and info and another story in the very thick file of the reason not to cheap out on parts when working on your rig(s).
 

Geotrash

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Thanks for following up. Keep an eye out though - the fuel pumps on these trucks don't last forever and one of the most common failure modes is when the fuel pressure regulator, which is in the tank with the pump, starts to fail. When it does, it will intermittently send higher than normal fuel pressure to your fuel rail and overwhelm the injectors, triggering the P0175 code. In other words, that code can be the proverbial sneeze, that leads to a cough, that leads to the flu and knocks you out. It's worth keeping an eye on that system with your scanner to make sure that code isn't continuing to be set - even if it doesn't do it often enough to trigger the CEL.
 

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