Code P0430, catalyst system Low efficiency (Bank 2)

Tiny
GRAMMYCOCO
  • MEMBER
  • 1999 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
Replaced o2 Sensor. Would like to let Roy know we still have not found the problem to flunk emissions. Found a bad spark plug, bought new, replaced and cured the misfire. Now a new code P0430, Catalyst System Low Efficiency (Bank 2).
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Friday, November 30th, 2018 AT 7:38 AM

11 Replies

Tiny
ASEMASTER6371
  • EXPERT
Glad you found the issue.

It sounds like it is fixed?

Roy
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Friday, November 30th, 2018 AT 1:50 PM
Tiny
GRAMMYCOCO
  • MEMBER
No, code P0430 (bank 2) and it flunked emissions again. After replacing the bad spark plug and putting in a new o2 sensor.
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Friday, November 30th, 2018 AT 3:29 PM
Tiny
ASEMASTER6371
  • EXPERT
430 is a bad catalytic converter for bank 2. It is not a sensor at all. It is the precious metals are worn out in the converter.

Bank 2 is the passenger side. They are separate converters.

Circuit Description
This diagnostic test is designed in order to measure the efficiency of the Three-Way Catalytic Converter (TWC) system. Catalytic converter efficiency is a measure of its ability to store oxygen after converting the levels of Hydrocarbon (HC), Carbon Monoxide (CO), and Oxides of Nitrogen (NOx) to less harmful gases. The Control Module (PCM/VCM) is able to evaluate the catalyst efficiency once the vehicle has met the enable criteria and the vehicle is at idle instead of steady cruise speeds as in the past. Once the conditions for running this DTC are met, the Control Module commands either a lean or rich air/fuel ratio depending on the current state of the exhaust oxygen level. The Control Module issues a rich command if the exhaust is currently lean, or a lean command if the exhaust is currently rich. After completion of the first command, a second and opposite command is issued.

For example, if the Control Module were to command a rich mixture, the upstream HO2S voltage would increase immediately. The rich mixture is delayed in reaching the downstream HO2S due to the conversion process occurring within the converter. The higher the efficiency, the more the delay before the rich or lean mixture is detected by the downstream O2 sensor. As a result of the lower conversion efficiency within a damaged or poisoned catalyst, the delay in the rich or lean mixture reaching the downstream O2 sensor is significantly shorter. This DTC monitors the amount of time required for both the upstream and downstream HO2S voltages to cross a calibrated voltage threshold in response to the rich or lean command.

Conditions for Running the DTC
No active secondary AIR DTCs
No active CMP sensor DTCs
No active ECT sensor DTCs
No active EGR DTCs
No active fuel trim DTCs
No active IAC DTCs
No active IAT sensor DTCs
No active MAF sensor DTCs
No active MAP sensor DTCs
No active O2 sensor DTCs
No active transmission DTCs
No active EVAP system DTCs
No active TP sensor DTCs
No active VS sensor DTCs
No active misfire DTCs
No active ignition DTCs
The engine speed is 1100 RPM or more for more than 44 seconds since last idle period
The engine has been running for at least 360 seconds and the long term fuel trim is stable
The predicted catalyst temperature is at least 390 C (734 F)
The system is in closed loop
The BARO is 72 kPa or more
The IAT is between -7-75 C (19-167 F)
The ECT is between 75-117 C (167-243 F)
The engine has been idling for less than 120 seconds
The actual engine speed is within 100 RPM of the desired idle speed

Conditions for Setting the DTC
The VCM determines that the oxygen storage capacity of the catalyst has degraded below a calibrated threshold

Action Taken When the DTC Sets
The Control Module illuminates the Malfunction Indicator Lamp (MIL) the first time the diagnostic runs and fails.
The Control Module will set the DTC and records the operating conditions at the time the diagnostic fails. The Control Module stores the failure information in the scan tools Freeze Frame and/or the Failure Records.

Conditions for Clearing the MIL/DTC
The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
A history DTC will clear if no fault conditions have been dejected for 40 warm-up cycles (coolant temperature has risen 22 C (40 F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70 C (158 F) during the same ignition cycle).
Use the scan tool Clear Information function.

Diagnostic Aids
The use of fuel with a high sulfur content or lead can degrade a marginal converters performance. Be sure to check fuel quality.
An intermittent may be caused by any of the following conditions:
A poor connection
Rubbed through wire insulation
A broken wire inside the insulation

Thoroughly check any circuitry that is suspected of causing the intermittent complaint. Refer to Intermittents and Poor Connections Diagnosis. See: Computers and Control Systems > Symptom Related Diagnostic Procedures

Test Description
The numbers below refer to the step numbers in the diagnostic table.
3. This table checks for conditions that can cause the Three-way Catalytic Converter efficiency to appear degraded. Inspect and repair exhaust system as necessary.
6. Before the Three-Way Catalytic Converter is replaced, make sure that the following conditions are not present:
Misfire.
High engine oil consumption or coolant consumption.
Retarded spark timing or weak spark.

Roy
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Friday, November 30th, 2018 AT 3:38 PM
Tiny
GRAMMYCOCO
  • MEMBER
Thank you so much. We will review this in the morning when our minds are fresh. We are exhausted and have snow to contend with tonight.
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Friday, November 30th, 2018 AT 4:18 PM
Tiny
ASEMASTER6371
  • EXPERT
You are welcome.

Roy
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Friday, November 30th, 2018 AT 4:19 PM
Tiny
GRAMMYCOCO
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We are going to replace the thermostat and temperature sensor next. It still did not pass emissions. Have not checked newest code. Thank you for all your help.
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Tuesday, December 4th, 2018 AT 1:34 PM
Tiny
ASEMASTER6371
  • EXPERT
Did you replace the cat converter? Did you set all the monitors?

Did the light come back on for the same code?

What brand catalytic converter did you use?

Roy
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Tuesday, December 4th, 2018 AT 1:50 PM
Tiny
GRAMMYCOCO
  • MEMBER
We did not replace catalytic converter. We have not read newest code yet.
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Tuesday, December 4th, 2018 AT 3:48 PM
Tiny
ASEMASTER6371
  • EXPERT
Okay, as I stated before, you need the catalytic converter replaced if you want to pass emissions.

Roy
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Wednesday, December 5th, 2018 AT 2:52 AM
Tiny
GRAMMYCOCO
  • MEMBER
Hello Roy,

Same 1999 Tahoe problems. We put a temperature sensor and a new thermostat in then drove it for awhile and a new code came up and it is running rough again. Code P0174 Any suggestions for that one?
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Monday, December 10th, 2018 AT 12:54 PM
Tiny
ASEMASTER6371
  • EXPERT
174 is a lean code for bank 2. That is the passenger side of the motor.

I would look for any vacuum leaks, possible bad injector or low fuel pressure.

You will need this resolves as well as the catalytic converter.

Roy

174

Circuit Description
In order to provide the best possible combination of driveability, fuel economy, and emission control, the vehicle uses a closed loop air and fuel metering system. While in closed loop, the VCM monitors the oxygen sensor signal voltage. The VCM adjusts the fuel delivery based on a signal voltage. The long and short term fuel values, which a scan tool can monitor, indicates a change made to the fuel delivery. Ideal fuel trim values are around 0% (128 counts); if the oxygen sensor signal indicates a lean condition, the VCM adds fuel. This results in fuel trim values above 0%. If the oxygen sensor detects a rich condition, the fuel trim values will read below 0%. This indicates that the VCM is reducing the amount of fuel delivered. The VCM sets this DTC when an excessively lean condition is detected.

Conditions for Running the DTC
No active O2 sensor DTCs
No active TP sensor DTCs
No active MAP sensor DTCs
No active EGR DTCs
No active EVAP system DTCs
No active ECT sensor DTCs
No active MAF sensor DTCs
No active IAT sensor DTCs
No active VS sensor DTCs
No active misfire DTCs
Throttle position less than 70%
Engine speed is between 575 and 4,000 RPM
The BARO greater than 70 kPa
The ECT is between 75 and 114 C (167-237 F)
The MAP is between 22 and 85 kPa.
The IAT is between 8 and 76 C (46-169 F)
The MAF is between 3 and 85 g/s
The vehicle speed less than 85 MPH

Conditions for Setting the DTC
The average of the short term fuel trim values over a period of 120 seconds indicates that a lean condition is present.

Action Taken When the DTC Sets

Important: To complete a trip cycle for the fuel trim diagnostic, the fuel trim diagnostic test must enable and run according to the above enable criteria and the conditions for setting. A trip is not considered complete until the fuel trim diagnostic has run by the VCM.

When the current DTC initially sets, a software flag indicating an emissions related fault sets for 3 trips. The flag will clear provided the lean condition is no longer present. However, if the VCM detects the conditions for setting the current DTC during a trip while the flag is still set, the VCM turns on the MIL (Malfunction Indicator Lamp). The MIL remains on during all of the subsequent trips until the DTC has been cleared by service or the lean condition has not been detected and the conditions for checking the fuel trim have been met for 3 consecutive trips.

Conditions for Clearing the MIL/DTC
The Control Module turns OFF the MIL after 3 consecutive drive trips when the test has Run and Passed.
A history DTC will clear if no fault conditions have been detected for 40 warm-up cycles (coolant temperature has risen 22 C (40 F) from the start-up coolant temperature and the Engine Coolant Temperature is more than 70 C (158 F) during the same ignition cycle).
Use the scan tool Clear Information function.

Diagnostic Aids
If using the diagnostic tables does not isolate the problem, try monitoring the LT fuel trim and fuel trim cell while operating the vehicle under various loads. This may isolate the condition which caused the setting of the current DTC.

A condition that causes the DTC P0300 Engine Misfire Detected may also set the current DTC; conversely an extremely lean condition which sets the current DTC can cause a misfire at idle and the DTC P0300 to set. If the cause of the current DTC cannot be determined and the DTC P0300 is also set, refer to DTC P0300 Engine Misfire Detected. See: A L L Diagnostic Trouble Codes ( DTC ) > P Code Charts > P0300

Typical Fuel Trim Values
The Fuel Trim Values table indicates the typical fuel adjustment values as displayed on a scan tool. Negative values (Rich condition) indicate that the injector pulse width is being decreased in order to lean out the fuel mixture. Positive values (Lean condition) indicate that the injector pulse width is being increased in order to richen the fuel mixture.

Test Description
The numbers below refer to step numbers on the diagnostic table.
2. A more negative value indicates the VCM is leaning the fuel mixture (Rich condition), and a more positive value indicates the VCM is richening the fuel mixture (Lean condition).
5. Visually and physically check the items that can cause a lean condition in order to determine the cause of the DTC being set.
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Monday, December 10th, 2018 AT 1:18 PM

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