Fuel System > Engine Control System > P0105 Barometric Pressure Sensor Circuit

Component Location

General Description

The amount of intake air flow must be inputted to PCM in order to determine the fuel injection quantity. To measure the pressure inside of intake manifold, MAFS is used at idle and MAPS is required during acceleration. MAPS(Manifold Absolute Pressure) calculates the amount of air indirectly as measuring the pressure inside of intake manifold. This mechanism is also called Speed-Density Type.MAPS transfers analog output signal which is proportional to the change of intake manifold pressure, then, with this signal and RPM, PCM calculates the amount of intake air flow. MAPS is mounted on surge tank to measure the pressure inside of intake manifold, and it consists of a piezo electric element and hybrid IC which amplifies output signal from the element. A piezo electric element is a sort of a diaphragm using piezo electric effect. One side of the diaphragm is surrounded with vacuum chamber while intake pressure is applied to the other side. Thus, signals are output by the transformation of diaphragm according to the change of pressure inside of intake manifold.

DTC Description

If the signal output of MAP sensor is stuck under enable conditions, PCM determines that a fault exists and a DTC is stored. MIL(Malfunction Indication Lamp) turns on when the malfunction lasts till consecutive 2 driving cycle.

DTC Detecting Condition

Item

Detecting Condition

Possible cause

DTC Strategy

•	Monitor the MAP sensor's signal

•	Faulty MAPS

Enable Conditions

•	No Disabling Fault Present

•	Shutdown time > 20 minutes

•	Engine running

Thresh old value

•	The difference between the signal at key-on and the signal at engine start <0.5 kPa

Diagnosis Time

•	For 3 seconds out of 5 seconds

MIL On Condition

•	2 driving cycles

Specification

Pressure(kPa)	20	35	60	95	101.32
Voltage(V)	0.789	1.382	2.369	3.75	4
Tolerance(V)	± 0.045

Schematic Diagram

Signal Waveform And Data

It is necessary that MAPS should be checked along with TPS. Because The MAP/TPS Rationality Diagnostic is comprised of two tests. A deceleration test is performed to provide a robust method for detection of an altitude compensated MAP value that is too high for the deceleration condition. The second test compares the altitude compensated MAP value to both high and low limits, dependent upon throttle position and engine speed. When the MAP value is out of the threshold range, the MAP/TPS system is determined to be failed.

Monitor DTC Status

Check DTC Status

(1)	Connect scantool to Data Link Connector(DLC).

(2)

IG "ON".

(3)	Select "DTC" button, and then Press "DTC Status" to check DTC's information from the DTCs menu.

(4)	Read "DTC Status" parameter.

(5)

Is parameter displayed "Present fault"?

	▶ Go to "Component Inspection" procedure.
	▶ Fault is intermittent caused by PCM memory was not cleared after repair. Erase DTC and drive the vehicle to satisfy the enable condition then,go to " Component Inspection" procedure.

Component Inspection

Check MAPS Performance

(1)	IG "OFF" and install scantool.

(2)	Connect probe to MAPS and TPS to check signal waveform by using oscilloscope function.

(3)

ENG "ON" and monitor signal waveform during acceleration and deceleration.

Specificaton :

Pressure(kPa)	Voltage(V)	Tolerance(V)
20	0.789	± 0.045
35	1.382
60	2.369
95	101.32
3.75	4

(4)

Is the measured signal waveform(MAP/TPS Rationality) O.K ?

	▶ Go to "Verification of Vehicle Repair" procedure.
	▶ Substitute with a known - good MAPS and check for proper operation. If the problem is corrected, replace MAPS and go to "Verification of Vehicle Repair" procedure.

Verification Of Vehicle Repair

After a repair, it is essential to verify that the fault has been corrected.

1.	Connect scantool and select "DTC" button.

2.	Press "DTC Status" button and confirm that "DTC Readiness Flag" indicates "Completed". If not, drive the vehicle within conditions noted in the freeze frame data or enable conditions

3.	Read "DTC Status" parameter

Is parameter displayed "History(Not Present) fault"?

	▶ System performing to specification at this time. Clear the DTC
	▶ Go to the applicable troubleshooting procedure.