The Engine Scan Tool Data Definitions contains a brief description of all engine related parameters available on the scan tool.

AC High Side Pressure: This parameter displays the high side pressure of the air conditioning (A/C) system based on the signal from the A/C high side pressure sensor.

AC Pressure Sensor: This parameter displays the voltage from the A/C high side pressure sensor signal circuit to the control module.

AC Request: This parameter indicates the status of the A/C switch on the instrument panel (IP). The scan tool parameter is Yes when AC has been selected.

AC Relay Command: The parameter indicates On whenever the powertrain control module (PCM) energizes the A/C compressor clutch relay.

Air Fuel Ratio: This parameter indicates air to fuel ratio calculated from fuel control oxygen sensor input. The ideal air fuel ratio under normal engine power demand is 14.7:1.

APP Angle: The scan tool range is 0-100 percent. The scan tool displays the amount of throttle opening in percentage. At closed throttle the scan tool displays zero percent. At wide open throttle (WOT) the scan tool displays approximately 80 percent.

APP at Idle: This parameter displays what the control module has determined to be the engine status based on input from the APP sensor. The scan tool parameter indicates Yes when the engine is operating at idle speeds.

APP Sensor 1: The scan tool displays 0-5 volts. The scan tool displays the accelerator pedal position in volts. With the pedal at rest, APP sensor 1 displays about 0.5 volts. At wide open throttle (WOT) APP sensor 1 displays about 5.0 volts.

APP Sensor 2: The scan tool displays 0-5 volts. The scan tool displays the accelerator pedal position in volts. With the pedal at rest, APP sensor 2 displays about 0.25 volts. At wide open throttle (WOT) APP sensor 2 displays about 2.5 volts.

BARO: The scan tool range 0-125 kPa. The barometric pressure (BARO) sensor measures the changes in atmospheric pressure. This parameter will read approximately 95 to 105 kPa at sea level.

Brake Switch: The brake switch controls the operation of the brake lamp circuit and sends a signal to the powertrain control module (PCM). When the brake pedal is depressed, the brake switch is Applied, CLOSED, and the brake lamps illuminate. When the brake pedal is released, the brake switch OPENS and the scan tool indicates Released.

Calculated Converter Temperature: The scan tool range is 300-950°C (572-1,742°F). This parameter displays the catalytic converter temperature as calculated by the control module. Since this temperature is calculated, ignore any value when the engine is below normal operating temperature. The vehicle may need to be driven in order to provide enough information for the control module to calculate the temperature accurately.

Crankshaft Position Sensor A: The scan tool display is Counts--from 0 to 3. This parameter displays a rolling count, when the PCM is receiving and using the CKP sensor A position signal. Normal engine operation is for the PCM to use the sensor A signal for crankshaft position, and ignore the sensor B input. The scan tool displays only the signal the PCM is using to determine crankshaft position. Therefore sensor A counts will be changing and sensor B counts will be fixed at zero.

Crankshaft Position Sensor B: The scan tool display is Counts--from 0 to 3. This parameter displays a rolling count only when the PCM is calculating crankshaft position from the CKP sensor B signal. CKP sensor B is normally fixed at zero. The PCM software is designed to use the sensor A signal for crankshaft position, and ignore the sensor B signal. If the sensor A signal is missing or irregular, the PCM will use the sensor B signal and display a rolling count on the sensor B scan tool parameter.

Cruise Brake Switch: This parameter indicates the state of the cruise brake switch that is controlled by the position of the brake pedal. The normal state of the switch is CLOSED, when the brake pedal is not depressed and the scan tool will display Released. The cruise brake switch is OPEN, when the brake pedal is depressed and the scan tool display is Applied.

Cruise Engaged: This parameter displays the status of the cruise control system as determined by the control module.

Cruise Resume/Accel. Switch: This parameter displays the state of the cruise controls resume/accel switch input to the control module.

Cruise Set/Coast Switch: This parameter displays the state of the cruise controls set/coast switch input to the control module.

Decel Fuel Cutoff: The Decel Fuel Cutoff parameter indicates when the control module is operating the fuel injectors in the fuel cutoff mode. When the operating in the fuel cutoff mode, fuel injector output is stopped and the Decel Fuel Cutoff parameter should read Active. The Decel Fuel Cutoff parameter should read Inactive during all other fueling conditions.

Desired Idle Speed: The desired idle speed is a PCM internal parameter which indicates the PCM requested idle speed. If the engine is not running, this number indicated is not valid.

ECT Sensor 1: The scan tool range is -40 to +152°C (-40 to +419°F). The engine coolant temperature (ECT) sensor is a thermistor which changes internal resistance as the temperature changes. When the sensor is cold, internal resistance high, the powertrain control module (PCM) monitors a high signal voltage and interprets the voltage as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine.

ECT Sensor 2: The scan tool range is -40 to +152°C (-40 to +419°F) / 0.0-5.0 Volts. The engine coolant temperature (ECT) sensor is a thermistor which changes internal resistance as the temperature changes. When the sensor is cold, internal resistance high, the powertrain control module (PCM) monitors a high signal voltage and interprets the voltage as a cold engine. As the sensor warms, internal resistance decreases, the voltage signal decreases and the PCM interprets the lower voltage as a warm engine. The ECT sensor 2 is located on the radiator side of the thermostat and typically reads a lower engine coolant temperature than ECT sensor 1.

Engine at Operating Temperature: This parameter will display Yes when the engine coolant temperature is 80°C (176°F) or more.

Engine Load: The scan tool range is 0-100 percent. This parameter indicates the engine load based upon the manifold absolute pressure. The higher the percentage, the more load the engine is under.

Engine Run Time: This parameter displays the time elapsed since the engine was started.

Engine Oil Life Left: This parameter displays the amount engine oil life remaining before requiring an oil change. This number is calculated by the control module based on inputs from various sensors.

Engine Speed: The scan tool range is 0-10,000 RPM. The powertrain control module (PCM) computes engine speed from the ignition reference pulses. The engine speed should remain close to the desired idle under various engine loads with the engine idling.

EVAP Purge Solenoid DC: The scan tool range is 0-100 percent. This parameter EVAP Purge Solenoid Duty Cycle (DC) indicates the percent of time the (EVAP) canister purge solenoid valve is ON.

EVAP Vent Solenoid: This parameter indicates when the PCM is turning ON the EVAP canister vent solenoid. The scan tool indicates ON when the solenoid is commanded ON.

EGR Duty Cycle: The scan tool range is 0-100 percent. The exhaust gas recirculation (EGR) duty cycle specifies the EGR valve on, valve open, time rate within a certain set cycle. Zero percent means that the valve is completely closed while a 100 percent is a fully open valve.

EGR Sensor: The scan tool range is 0.0-5.0 volts. The EGR valve pintle or plunger movement is monitored by a position sensor. When the EGR valve is closed, the sensor voltage is between 1.0-1.5 volts.

Fan Control 1 Command: This parameter indicates that the PCM is turning ON the fan 1 relay. When the fan 1 relay is ON, both engine cooling fans operate at LOW speed. The PCM will command the fan 1 relay on when AC is selected. The PCM will command the fan 1 relay on when the coolant temperature reaches 98°C (208°F). Once energized the fan 1 relay remains ON until the coolant temperature drops to below 95°C (203°F) or AC is switched Off.

Fan Control 2 Command: This parameter indicates that the PCM is turning ON the fan 2 relay. When the fan 2 relay is ON, both engine cooling fans operate at HIGH speed.The PCM will command the fan 2 relay on when AC system pressure is more than 2,100 kPa. The PCM will command the fan 2 relay on when the coolant temperature reaches 102°C (215°F). Once energized the fan 2 relay remains ON until the coolant temperature drops to below 99°C (210°F) or the AC pressure is below 1,400 kPa.

Fuel Level: The scan tool displays liters or gallons. This parameter indicates approximate of fuel in the fuel tank.

Fuel Level Sensor: The scan tool range is 0-100 percent. This parameter indicates approximate fuel level in the fuel tank. The detectable range of the fuel level sensor is set as 0 to 100 percent, however, with some models whose fuel tank capacity is smaller, the indicated fuel level may be only 70 percent even when the fuel tank is full.

Fuel Level Sensor: The scan tool range is 0- volts. This parameter indicates approximate fuel level in the fuel tank. The detectable range of the fuel level sensor is set as 0 to 100 percent, however, with some models whose fuel tank capacity is smaller, the indicated fuel level may be only 70 percent even when the fuel tank is full.

Fuel Pump Relay Command: This parameter indicates whether the powertrain control module (PCM) is requesting the fuel pump ON or OFF.

Fuel Tank Pressure Sensor: The scan tool range is 0-5 Volts/-32.0 mmHg to +16.8 mmHg (-17.1 inH2O to +9.0 inH2O). This parameter indicates the pressure in the fuel tank. High voltage indicates negative pressure. Low voltage indicates positive pressure.

Generator F Terminal: This parameter displays the amount of generator on-time as commanded by the control module. The higher the percentage the greater the generator output.

Generator L Terminal: This parameter displays the control module commanded state of the voltage regulator on the generator.

HO2S Bank 1 Sensor 1: The scan tool range is 0.0-2.0 Lambda. This parameter displays the lambda output from the heated oxygen sensor (HO2S) to the control module. A low lambda indicates a rich exhaust, while high lambda indicates a lean exhaust.

HO2S Bank 1 Sensor 2: The scan tool range is 0-1275 mV. The bank 1 rear heated oxygen sensor 2 represents the exhaust oxygen output voltage beyond the catalytic converter. This voltage will remain inactive or appear lazy within a range 100 mV, lean exhaust, and 900 mV, rich exhaust, when the system is operating in Closed Loop.

HO2S Bank 2 Sensor 1: The scan tool range is 0.0-2.0 Lambda. This parameter displays the lambda output from the heated oxygen sensor (HO2S) to the control module. A low lambda indicates a rich exhaust, while high lambda indicates a lean exhaust.

HO2S Bank 2 Sensor 2: The scan tool range is 0-1275 mV. The bank 2 rear heated oxygen sensor represents the exhaust oxygen output voltage beyond the catalytic converter. This voltage will remain inactive or appear lazy within a range 100 mV, lean exhaust, and 900 mV, rich exhaust, when the system is operating in Closed Loop.

HO2S Heater Bank 1 Sensor 1: This parameter indicates when the heater of the bank 1 oxygen sensor 1 is switched On.

HO2S Heater Bank 1 Sensor 2: This parameter indicates when the heater of the bank 1 oxygen sensor 2 is switched On.

HO2S Heater Bank 2 Sensor 1: This parameter indicates when the heater of the bank 2 oxygen sensor 1 is switched On.

HO2S Heater Bank 2 Sensor 2: This parameter indicates when the heater of the bank 2 oxygen sensor 2 is switched On.

Idle Increase Command (AC Request Only): This parameter indicates when the engine idle speed is being increased because of increased engine load from the AC compressor operation.

Ignition 1: This parameter indicates the ignition switched system voltage.

Injector PWM Bank 1: The scan tool range is 0 to 32.64 ms. This parameter indicates the amount of time a bank 1 fuel injector solenoid valve is open.

Injector PWM Bank 2: The scan tool range is 0 to 32.64 ms. This parameter indicates the amount of time a bank 2 fuel injector solenoid valve is open.

IAT Sensor 1: The scan tool range is -40 to +152°C (-40 to +419°F). The powertrain control module (PCM) converts the resistance of the intake air temperature (IAT) sensor to degrees. The PCM uses the intake air temperature (IAT) in order to adjust fuel delivery and spark timing according to incoming air density.

IAT Sensor 2: The scan tool range is -40 to +152°C (-40 to +419°F). The powertrain control module (PCM) converts the resistance of the intake air temperature (IAT) sensor to degrees. The PCM uses the intake air temperature (IAT) in order to adjust fuel delivery and spark timing according to incoming air density.

Intake Rocker Arm Actuator Solenoid Command: This parameter displays the commanded state of the intake rocker arm actuator solenoid.

Intake Rocker Arm Actuator Oil Pressure Switch: When the intake rocker arm actuator solenoid is On, engine oil should flow to the intake rocker arms and the rocker arm oil pressure switch. Oil pressure will turn On the intake rocker arm actuator oil pressure switch.

Knock Control: This parameters indicates when the control module is actively modifying ignition timing in response to knock sensor input.

Knock Sensor: The scan tool range is 0.0-3.9 volts. This parameters displays the voltage input to the control module from the knock sensor (KS). Voltage that is more than 0.0 is indicated only when knock is detected.

Long Term FT Bank 1: The scan tool displays a positive or a negative percentage. The powertrain control module (PCM) derives the Long Term fuel trim (FT) from the Short Term fuel trim value. The Long Term fuel trim represents a long-term correction of fuel delivery. A value of 0 percent indicates that the fuel delivery requires no compensation in order to maintain the PCM commanded air/fuel ratio. A negative value significantly less than 0 percent indicates that the fuel system is rich and the PCM is reducing the fuel delivery, decreasing the fuel injector pulse width. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel, increasing fuel injector pulse width. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Long Term FT Bank 2: The scan tool displays a positive or a negative percentage. The powertrain control module (PCM) derives the Long Term fuel trim (FT) from the Short Term fuel trim value. The Long Term fuel trim represents a long-term correction of fuel delivery. A value of 0 percent indicates that the fuel delivery requires no compensation in order to maintain the PCM commanded air/fuel ratio. A negative value significantly less than 0 percent indicates that the fuel system is rich and the PCM is reducing the fuel delivery, decreasing the fuel injector pulse width. A positive value significantly more than 0 percent indicates that a lean condition exists and the PCM compensates by adding fuel, increasing fuel injector pulse width. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Loop Status Bank 1: The Loop Status parameter will display one of the following conditions: OPEN LOOP: The HO2S Bank 1 Sensor 1 has not met all of the conditions necessary for Closed Loop operation. CLOSED LOOP: The powertrain control module (PCM) is using HO2S Bank 1 Sensor 1 as feedback for fuel control.

Loop Status Bank 2: The Loop Status parameter will display one of the following conditions: OPEN LOOP: The HO2S Bank 2 Sensor 1 has not met all of the conditions necessary for Closed Loop operation. CLOSED LOOP: The powertrain control module (PCM) is using HO2S Bank 2 Sensor 1 as feedback for fuel control.

Low Oil Pressure Switch: This parameter displays the status of the low engine oil pressure switch.

MAP Sensor: The scan tool range is 0-125 kPa/0.0-5.0 volts. The manifold absolute pressure (MAP) sensor measures the change in the intake manifold pressure from engine load, and speed changes. As intake manifold pressure increases, the intake vacuum decreases resulting in a higher kPa reading.

Misfire Current Cyl #1, #2, #3, #4, #5, #6: Indicates a count of the abnormal engine revolutions (misfire) for each cylinder.

Misfire History Cyl #1, #2, #3, #4, #5, #6: Indicates the stored or history count of the abnormal engine revolutions (misfire) for each cylinder.

Power Enrichment: This parameter displays the status of the operating mode of the control module used to increase fuel delivery during certain acceleration conditions.

Rough Road Detection: This parameter indicates Yes when the misfire diagnostic has determined that a rough road surface condition exists. Input from the CKP and CMP sensors indicates that the road surface may cause false engine misfire counts. During rough road detection the PCM uses certain filters in order to monitor engine misfire accurately.

Short Term FT Bank 1: The scan tool displays a positive or a negative percentage. The Short Term fuel trim (FT) represents a short-term correction to fuel delivery by the powertrain control module (PCM). The Short Term FT correction is driven by the fuel control oxygen sensor voltage. When the oxygen sensor (O2S) voltage remains less than 450 mV the PCM adds fuel and the Short Term FT parameter displays a positive percentage. When the oxygen sensor voltage stays at more than 450 mV the PCM subtracts fuel and the Short Term FT parameter displays a negative percentage. During an extended idle in high ambient temperatures the evaporative emission (EVAP) canister may purge, causing the Short Term FT to read in the negative range. This is a normal condition. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Short Term FT Bank 2: The scan tool displays a positive or a negative percentage. The Short Term fuel trim (FT) represents a short-term correction to fuel delivery by the powertrain control module (PCM). The Short Term FT correction is driven by the fuel control oxygen sensor voltage. When the oxygen sensor (O2S) voltage remains less than 450 mV the PCM adds fuel and the Short Term FT parameter displays a positive percentage. When the oxygen sensor voltage stays at more than 450 mV the PCM subtracts fuel and the Short Term FT parameter displays a negative percentage. During an extended idle in high ambient temperatures the evaporative emission (EVAP) canister may purge, causing the Short Term FT to read in the negative range. This is a normal condition. Fuel trim values at maximum authority may indicate an excessively rich or lean system.

Spark Advance: The scan tool range is -1 to +63 degrees. The scan tool displays the powertrain control module (PCM) controlled value that is being used to control the spark timing.

Start Up ECT: The scan tool range is -40 to +140°C (-40 to +284°F). This parameter displays what the ECT sensor temperature was when the engine was first started this ignition cycle.

TAC Limit Engine Power: The scan tool will indicate Yes when the throttle actuator control (TAC) system has fixed the engine speed below 1,500 RPM. A fault in the accelerator pedal position (APP) sensor circuit willcause the TAC Limit Engine Power

TAC Module Power Inhibit Feedback: This scan tool parameter displays the internal voltage of the TAC motor inhibit circuit. Normal circuit operation voltage is approximately 0.67 volts. Most DTC setting TAC system failures cause the inhibit circuit voltage to default to 0.0 volts. An open in the TAC module ground circuit can cause an inhibit circuit voltage of 0.96 volts.

Throttle Plate at Idle: This parameter indicates Yes when the position of throttle body throttle plate is at idle or the default closed position.

Throttle Plate at WOT: This parameter indicates Yes when the throttle body throttle plate is at the wide open throttle (WOT) position.

TP Angle: The scan tool range is 0-100 percent. The scan tool displays the amount of throttle opening in percentage. At closed throttle the scan tool displays zero percent. At wide open throttle (WOT) the scan tool displays approximately 80 percent. At normal engine idle speeds the TP angle is between 9-14 percent.

TPS Learned Value: The scan tool range is 0-100 percent. The TPS learned value is an assigned value by the PCM. The PCM calculates the value using the original TP position, plus any increase in angle as a result of a greater throttle plate opening to compensate for the buildup of carbon deposits. The typical TPS learned value is zero percent after reset. The value will increase as carbon deposits build up on the throttle plate.

Vehicle Speed: The scan tool range is 0-255 km/h (0-158 mph). This parameter displays the vehicle speed. The powertrain control module (PCM) receives reference pulses from the vehicle speed sensor (VSS) and converts the pulses into km/h and mph for display.