2 codes plz help
Thread Starter
Instructor
Joined: May 2009
Posts: 208
Likes: 0
From: castaic california
2 codes plz help
Just popped up this morning ,
1)p0420
2)p0128
I have a cheap lil obd2 scanner and the scanner states p0128 coolant temperature below thermostat regulation.. what can I doo to fix that? Is it something I should wory about? The p0420 I know its the oxygen sensor.. am I right? What can I doo to fix that? Thank you guys n gals.
1)p0420
2)p0128
I have a cheap lil obd2 scanner and the scanner states p0128 coolant temperature below thermostat regulation.. what can I doo to fix that? Is it something I should wory about? The p0420 I know its the oxygen sensor.. am I right? What can I doo to fix that? Thank you guys n gals.
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
Should tell us what year? This is from '02 Service Manual.
DTC P0128
Circuit Description
An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control and as an enabling criteria for some diagnostics.
The air flow coming into the engine is accumulated and used to determine if the engine has been driven within the conditions that would allow the engine coolant to heat normally to the thermostat regulating temperature. If the coolant temperature does not increase normally, or does not reach the regulating temperature of the thermostat, the diagnostics that use the engine coolant temperature as an enabling criteria may not run when expected.
If the engine coolant fails to reach a preset target temperature before a calculated air flow is accumulated, P0128 will set.
This DTC will only run once per ignition cycle within the enabling conditions.
Conditions for Running the DTC
DTCs P0100, P0101, P0103, P0110, P0111, P0112, P0113, P0116, P0117, P0118, P0125, P0500, P0501, P0502, P0503, P1114, or P1115 are not set.
The coolant temperature is -40°C (-40°F) or more.
The coolant temperature is less than 70°C (158°F).
The intake air temperature is -7°C (19°F) or more.
The engine running for more than 2 minutes and less than 22 minutes.
The vehicle speed is more than 8 km/h (5 mph) for more than 2.4 km (1.5 miles).
The mass air flow average reading is more than 23 g/s.
Conditions for Setting the DTC
The length of time for the engine coolant to reach a preset temperature has been exceeded.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
DTC P0128 is designed to detect a faulty thermostat.
Excessive coolant flow through the bypass hose to the throttle body may cause this DTC to set.
A skewed ECT sensor may cause a DTC P0128 to set.
A skewed intake air temperature (IAT) sensor may cause this DTC to set
DTC P0420 or P0430
Circuit Description
In order to maintain low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting NOx into nitrogen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2. HO2S bank 1 sensor 2, located in the exhaust stream past the 3-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 signal will be far less active than the signal that is produced by HO2S bank 1 sensor 1. This indicates that the 3-way catalytic converter's oxygen storage capacity is below an acceptable threshold.
The PCM performs this diagnostic during idle. When the conditions for running this DTC are met, the following conditions occurs:
The PCM captures the current rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions from rich to lean or from lean to rich, depending on the capture rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions a second time opposite the first air-to-fuel ratio transition.
The PCM captures the response time of the front and rear heated oxygen sensors when the air-to-fuel ratio transitions occur. The HO2S response time goes from less 300 mV to more than 600 mV, and from more than 600 mV to less than 300 mV.
The PCM measures the time it takes the rear HO2S voltage to cross a reference rich-to-lean threshold, minus the time it takes the front HO2S voltage to cross the same rich-to-lean threshold. The difference between the front HO2S time and the rear HO2S time is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
Conditions for Running the DTC
DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0131, P0133, P0134, P0135, P0137, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0300, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0410, P0440, P0502, P0503, P0506, P0507, P0606, P1120, P1133, P1134, P1153, P1154, P1220, P1336, P1415, P1416, or P1441 are not set.
The intake air temperature (IAT) is more than -7°C (19°F), but less than 75°C (167°F).
The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
The engine is operating.
The engine coolant temperature (ECT) is more than 75°C (167°F), but less than 117°C (243°F).
Since the end of the last idle period, the engine speed is more than 850 RPM for a minimum of:
17 seconds for manual transmissions
27 seconds for automatic transmissions
The Closed Loop fuel control is enabled.
Conditions for Setting the DTC
The PCM determines if oxygen storage capability of the catalytic converter has degraded to less than a calibrated threshold.
Action Taken When the DTC Sets
The malfunction indicator lamp (MIL) is turned ON.
A DTC is stored in memory.
The Freeze Frame/Failure Records are stored.
The Failure Records are updated after the first failure of each ignition cycle.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
DTC P0128
Circuit Description
An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control and as an enabling criteria for some diagnostics.
The air flow coming into the engine is accumulated and used to determine if the engine has been driven within the conditions that would allow the engine coolant to heat normally to the thermostat regulating temperature. If the coolant temperature does not increase normally, or does not reach the regulating temperature of the thermostat, the diagnostics that use the engine coolant temperature as an enabling criteria may not run when expected.
If the engine coolant fails to reach a preset target temperature before a calculated air flow is accumulated, P0128 will set.
This DTC will only run once per ignition cycle within the enabling conditions.
Conditions for Running the DTC
DTCs P0100, P0101, P0103, P0110, P0111, P0112, P0113, P0116, P0117, P0118, P0125, P0500, P0501, P0502, P0503, P1114, or P1115 are not set.
The coolant temperature is -40°C (-40°F) or more.
The coolant temperature is less than 70°C (158°F).
The intake air temperature is -7°C (19°F) or more.
The engine running for more than 2 minutes and less than 22 minutes.
The vehicle speed is more than 8 km/h (5 mph) for more than 2.4 km (1.5 miles).
The mass air flow average reading is more than 23 g/s.
Conditions for Setting the DTC
The length of time for the engine coolant to reach a preset temperature has been exceeded.
Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Diagnostic Aids
DTC P0128 is designed to detect a faulty thermostat.
Excessive coolant flow through the bypass hose to the throttle body may cause this DTC to set.
A skewed ECT sensor may cause a DTC P0128 to set.
A skewed intake air temperature (IAT) sensor may cause this DTC to set
DTC P0420 or P0430
Circuit Description
In order to maintain low emissions of hydrocarbons (HC), carbon monoxide (CO), and oxides of nitrogen (NOx), the engine controls system uses a 3-way catalytic converter. The catalyst within the converter promotes a chemical reaction, which oxidizes the HC and CO that are present in the exhaust gas. This reaction converts these chemicals into harmless water vapor and carbon dioxide. The catalyst also reduces NOx, converting NOx into nitrogen. The powertrain control module (PCM) monitors this process using heated oxygen sensor (HO2S) bank 1 sensor 2. HO2S bank 1 sensor 2, located in the exhaust stream past the 3-way catalytic converter, produces an output signal which indicates the oxygen storage capacity of the catalyst. This determines the catalyst's ability to effectively convert the exhaust emissions. If the catalyst is functioning correctly, the HO2S bank 1 sensor 2 signal will be far less active than the signal that is produced by HO2S bank 1 sensor 1. This indicates that the 3-way catalytic converter's oxygen storage capacity is below an acceptable threshold.
The PCM performs this diagnostic during idle. When the conditions for running this DTC are met, the following conditions occurs:
The PCM captures the current rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions from rich to lean or from lean to rich, depending on the capture rear HO2S rich-to-lean status.
The air-to-fuel ratio transitions a second time opposite the first air-to-fuel ratio transition.
The PCM captures the response time of the front and rear heated oxygen sensors when the air-to-fuel ratio transitions occur. The HO2S response time goes from less 300 mV to more than 600 mV, and from more than 600 mV to less than 300 mV.
The PCM measures the time it takes the rear HO2S voltage to cross a reference rich-to-lean threshold, minus the time it takes the front HO2S voltage to cross the same rich-to-lean threshold. The difference between the front HO2S time and the rear HO2S time is the oxygen storage capacity of the catalyst. This DTC sets if the time exceeds a predetermined threshold.
Conditions for Running the DTC
DTCs P0101, P0102, P0103, P0106, P0107, P0108, P0112, P0113, P0116, P0117, P0118, P0128, P0131, P0133, P0134, P0135, P0137, P0140, P0141, P0151, P0152, P0153, P0154, P0155, P0157, P0158, P0160, P0161, P0171, P0172, P0174, P0175, P0200, P0300, P0335, P0336, P0341, P0342, P0343, P0351-P0358, P0410, P0440, P0502, P0503, P0506, P0507, P0606, P1120, P1133, P1134, P1153, P1154, P1220, P1336, P1415, P1416, or P1441 are not set.
The intake air temperature (IAT) is more than -7°C (19°F), but less than 75°C (167°F).
The barometric pressure (BARO) is more than 74 kPa (10.7 psi).
The engine is operating.
The engine coolant temperature (ECT) is more than 75°C (167°F), but less than 117°C (243°F).
Since the end of the last idle period, the engine speed is more than 850 RPM for a minimum of:
17 seconds for manual transmissions
27 seconds for automatic transmissions
The Closed Loop fuel control is enabled.
Conditions for Setting the DTC
The PCM determines if oxygen storage capability of the catalytic converter has degraded to less than a calibrated threshold.
Action Taken When the DTC Sets
The malfunction indicator lamp (MIL) is turned ON.
A DTC is stored in memory.
The Freeze Frame/Failure Records are stored.
The Failure Records are updated after the first failure of each ignition cycle.
Conditions for Clearing the MIL/DTC
The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.
A current DTC, Last Test Failed, clears when the diagnostic runs and passes.
A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.
Clear the MIL and the DTC with a scan tool.
Thread Starter
Instructor
Joined: May 2009
Posts: 208
Likes: 0
From: castaic california
i have a 2001 c5 z06. i dont know but this may help. i woke up in a hurry and well in the morning it was kinda cold so i jumped in my car and took off to work. did it pop up because i didnt warm up the car before taking off?
