Isuzu KB P190. Manual - part 840

Engine Management – V6 – Diagnostics 

Page 6C1-2–82 

 

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DTC P0131 – O2 Sensor Circuit Low Voltage (Bank 1, Sensor 1) 

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DTC P0132 – O2 Sensor Circuit High Voltage (Bank 1, Sensor 1) 

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DTC P0133 –  

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DTC P0135 – O2 Sensor Heater Circuit Range / Performance (Bank 1, Sensor 1) 

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DTC P0137 – O2 Sensor Circuit Low Voltage (Bank 1, Sensor 2) 

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DTC P0138 – O2 Sensor Circuit High Voltage (Bank 1, Sensor 2) 

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DTC P0140 – O2 Sensor Circuit No Activity Detected (Bank 1, Sensor 2) 

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DTC P0141 – O2 Sensor Heater Circuit Range / Performance (Bank 1, Sensor 2) 

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DTC P0150 – O2 Sensor Circuit Malfunction (Bank 2, Sensor 1) 

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DTC P0151 – O2 Sensor Circuit Low Voltage (Bank 2, Sensor 1) 

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DTC P0152 – O2 Sensor Circuit High Voltage (Bank 2, Sensor 1) 

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DTC P0155 –O2 Sensor Heater Circuit Range / Performance (Bank 2, Sensor 1) 

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DTC P0157 – O2 Sensor Circuit Low Voltage (Bank 2, Sensor 2) 

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DTC P0158 – O2 Sensor Circuit High Voltage (Bank 2, Sensor 2) 

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DTC P0160 – O2 Sensor Circuit No Activity Detected (Bank 2, Sensor 2) 

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DTC P0161 – O2 Sensor Heater Circuit Range / Performance (Bank 2, Sensor 2) 

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DTC P2243 – O2 Sensor Voltage Signal Circuit Malfunction (Bank 1, Sensor 1) 

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DTC P2247 – O2 Sensor Voltage Signal Circuit Malfunction (Bank 2, Sensor 1) 

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DTC P2270 – O2 Sensor Lean / Rich Switch Signal Malfunction (Bank 1, Sensor 2) 

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DTC P2271 – O2 Sensor Rich / Lean Switch Signal Malfunction (Bank 1, Sensor 2) 

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DTC P2272 – O2 Sensor Lean / Rich Switch Signal Malfunction (Bank 2, Sensor 2) 

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DTC P2273 – O2 Sensor Rich / Lean Switch Signal Malfunction (Bank 2, Sensor 2) 

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DTC P2297 – O2 Sensor Range / Performance During Deceleration Fuel Cutoff (Bank 1, Sensor 1) 

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DTC P2298 – O2 Sensor Range / Performance During Deceleration Fuel Cutoff (Bank 2, Sensor 1) 

Circuit Description 

The engine control relay applies positive voltage to the heater ignition voltage circuits of the HO2S. The ECM applies a 
pulse width modulated (PWM) ground to the heater control circuit of the HO2S through a device within the ECM called a 
driver, to control the HO2S rate of heating. 

HO2 Sensor 2 

The ECM applies a voltage of approximately 450 mV between the reference signal circuit and low reference circuit of the 
HO2S while the sensor temperature is less than the operating range. 

Once the HO2S reaches operating temperature, the sensor varies this reference signal voltage, which constantly 
fluctuates between the high voltage output and the low voltage output. 

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The low voltage output is 0 – 450 mV, which occurs if the air fuel mixture is lean. 

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The high voltage output is 450 – 1,000 mV, which occurs if the air fuel mixture is rich. 

The ECM monitors, stores and evaluates the HO2S voltage fluctuation information to determine the level of oxygen 
concentration in the exhaust. 

HO2 Sensor 1 

The ECM maintains the voltage between the reference signal circuit and low reference circuit of the HO2S 1 to about 
450 mV by increasing or decreasing the oxygen content in the HO2S diffusion gap. To achieve this, the ECM controls 
the current applied to the oxygen pumping cell in the HO2S 

Engine Management – V6 – Diagnostics 

Page 6C1-2–83 

 

The pumping current required to maintain the HO2S 1 signal circuit voltage to about 450 mV is proportional to the level 
of oxygen concentration in the exhaust gas. 

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If the air/fuel mixture in the exhaust is balanced (lambda = 1), the oxygen pumping cell current is zero. 

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If the exhaust gas in the HO2S 1 diffusion gap is lean, the ECM applies a positive current to the oxygen pumping 
cell to discharge oxygen from the diffusion gap. 

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If the exhaust gas in the HO2S 1 diffusion gap is rich, the ECM applies a negative current to the oxygen pumping 
cell to draw oxygen into the diffusion gap. 

The ECM monitors and evaluates the oxygen pumping current to determine the level of oxygen concentration in the 
exhaust. 

An HO2S reference circuit DTC sets if the ECM detects the HO2S signal voltage is outside the predetermined range for 
a specified period. 

Conditions for Running the DTC 

DTC P0130, P0131, P0132, P0137, P0138, P0140, P0150, P0151 or P0152 

Run continuously once the following conditions are met: 

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The ignition voltage is 10.0 – 16.0 V. 

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The engine is running. 

DTC P0135 and P0155 

Condition 1 

Run continuously once the following conditions are met: 

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DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0101, P103, P0121, P0122, P0123, P0131, P0132, P0151, 
P0152, P0221, P0222, P0223, P0335, P0336, P0338, P2237, P2240, P2243, P2247, P2251 and P2254 ran and 
passed. 

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The ignition voltage is 10.0 – 16.0 V. 

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The HO2S is at operating temperature. 

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The ECM internal sensing element resistance test is enabled. 

Condition 2 

Run continuously once the following conditions are met: 

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DTCs P0030, P0031, P0032, P0050, P0051, P0052, P0101, P103, P0121, P0122, P0123, P0131, P0132, P0151, 
P0152, P0221, P0222, P0223, P0335, P0336, P0338, P2237, P2240, P2243, P2247, P2251 and P2254 ran and 
passed. 

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The ignition voltage is 10.0 – 16.0 V. 

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The HO2S is at operating temperature. 

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The ECM internal sensing element resistance test is enabled. 

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The fuel injectors are not disabled. 

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If the engine is operating and the ignition is turned off, the engine must be off for at least 5 minutes for this DTC to 
run. 

DTC P0137 and P0157 

Run continuously once the following conditions are met: 

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DTCs P0117, P0118, P0125 and P0128 ran and passed. 

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The engine is operating for longer than two minutes. 

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The ignition voltage is 10.0 – 16.0 V. 

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The HO2S is at operating temperature. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–84 

 

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The calculated exhaust temperature is 250ºC – 800ºC. 

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The engine coolant temperature is less than 40ºC at start-up and greater than 60ºC when the ignition was turned 
off last ignition cycle. 

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The fuel tank level is greater than 25 percent. 

DTC P0138 and P0158 

Run continuously once the following conditions are met: 

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The engine is operating for longer than two minutes. 

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The ignition voltage is 10.0 – 16.0 V. 

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The HO2S is at operating temperature. 

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The calculated exhaust temperature is 250ºC – 800ºC. 

DTC P0140 and P0160 

Run continuously once the following conditions are met for longer than 90 seconds: 

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The engine is operating. 

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The ignition voltage is 10.0 – 16.0 V. 

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The calculated exhaust temperature is 250º C – 800º C. 

DTC P0141 and P0161 

Run continuously once the following conditions are met: 

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DTCs P0036, P0037, P0038, P0056, P0057, and P0058 ran and passed. 

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DTCs P0137, P0138, P0140, P0157, P0158, or P0160 are not set. 

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The engine is operating. 

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The ECM internal sensing element resistance is valid. 

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The fuel system is not in decel fuel shut-off. 

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The intake air temperature is greater than -7ºC. 

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If the engine is operating and the ignition is turned off, the engine must be off for at least 5 minutes for this DTC to 
run. 

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The ignition voltage is 10.0 – 16.0 V. 

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The calculated exhaust temperature is 360ºC – 500ºC. 

DTC P2243 and P2247 

Run continuously once the following conditions are met: 

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DTCs P0030, P0031, P0032, P0050, P0051 and P0052 ran and passed. 

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The ECM internal sensing element resistance is greater than 570 

Ω. 

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The HO2S is at operating temperature. 

DTC P2270 and P2272 

Run continuously once the following conditions are met: 

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DTCs P0036, P0037, P0038, P0056, P0057, P0058, P0137, P0138, P0140, P0141, P0157, P0158, P0160, P0161, 
P0342, P0343, P0443, P0458 and P0459 ran and passed. 

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The engine is running. 

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The HO2S 2 are at operating temperature for longer than 10 seconds. 

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The long term fuel control is enabled. 

Engine Management – V6 – Diagnostics 

Page 6C1-2–85 

 

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The MAF sensor is greater than 10 g/s. 

DTC P2297 and P2298 

Condition 1 

Run continuously once the following conditions are met: 

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DTCs P0130 and P0150 ran and passed. 

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The HO2S 1 are at operating temperature. 

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The desired HO2S 1 signal is less than 1.6 lambda. 

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The internal ECM HO2S 1 signal voltage is less than 4.81 V. 

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The fuel injectors are enabled. 

Condition 2 

Run continuously once a decel fuel cut-off has occurred 11 times with successful adjustments 

Conditions for Setting the DTC 

DTC P0130 and P0150 

The ECM detects the HO2S signal voltage is out of range. 

DTC P0131 and P0151 

The ECM internal HO2S voltage is less than the specified threshold. 

DTC P0132 and P0152 

The ECM internal HO2S voltage is less than the specified threshold. 

DTC P0135 and P0155 

Condition 1 

The ECM internal HO2S sensing element resistance is less than the specified threshold for longer than 15 seconds. 

Condition 2 

The ECM detects the calculated HO2S temperature is greater than a predetermined threshold. 

DTC P0137 and P0157 

The ECM detects the HO2S signal voltage is less than 60 mV. 

DTC P0138 and P0158 

The ECM detects the HO2S signal voltage is greater than 1050 mV. 

DTC P0140 and P0160 

The ECM detects one of the following conditions: 

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The HO2S signal voltage is 400 – 500 mV for longer than 5 minutes, or 

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the internal resistance of the HO2S is greater than 40,000 

Ω when the calculated exhaust temperature is greater 

than 600ºC. 

DTC P0141 and P0161 

The ECM detects the HO2S internal resistance is not within the expected range for longer than 6 seconds.