B1257
DTC B1257 AQS OPENComponent Location:
GENERAL DESCRIPTION
AQS (Air Quality System) keeps air inside in the most suitable state for driver. In polluted area AQS detects hazardous gas and intercepts inflow automatically, Inversely, In fresh area it allows the inflow of air to prevent the shortage of air and the accumulation of carbon dioxide. AQS sensor is located at front side of condenser and once hazardous gas is detected, it delivers the voltage signal to A/C controller for closing intake door.
DTC DESCRIPTION
The A/C controller sets DTC B1257 if there is an open circuit in AQS sensor signal harness or the measured voltage value of sensor is more than threshold value.
DTC Detecting Condition:
Specification:
MONITOR SCANTOOL DATA
1. Connect scantool to Data Link Connector (DLC).
2. Engine "ON"
3. Monitor the "AQS sensor Parameter on the Scantool. While making hazardous gas such as tobacco fumes around the AQS sensor.
4. Are the DTC B1257 present and is parameter of "AQS SENSOR" fixed?
YES - Go to "Inspection" procedure.
NO - Fault is intermittent caused by poor contact in the sensor's and/or A/C controller's connector or was repaired and A/C controller memory was not cleared. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
TERMINAL AND CONNECTOR INSPECTION
1. Many malfunctions in the electrical system are caused by poor harness and terminals.
Faults can also be caused by interference from other electrical systems, and mechanical or chemical damage.
2. Thoroughly check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage.
3. Has a problem been found?
YES - Repair as necessary and go to "Verification of Vehicle Repair" procedure.
NO - Go to "Signal circuit inspection" procedure.
SIGNAL CIRCUIT INSPECTION
1. Check for open in harness.
1. Ignition "OFF"
2. Disconnect AQS sensor.
3. Measure resistance between terminal "4" of AQS sensor and terminal "2" of A/C Control Unit.
Specification : Approx. 0 ohms
4. Is the measured resistance within specifications?
YES - Go to "Ground circuit Inspection" procedure.
NO - Check for open in harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
GROUND CIRCUIT INSPECTION
1. Check for open in ground harness.
1. Ignition "OFF"
2. Disconnect AQS sensor.
3. Measure resistance between terminal "5" of AQS sensor and chassis ground.
Specification Approx. 0 ohms
4. Is the measured resistance within specifications?
YES - Go to "Component Inspection" procedure.
NO - Check for open in ground harness. Repair as necessary and go to "Verification of Vehicle Repair" procedure.
COMPONENT INSPECTION
1. Check AQS sensor.
1. Engine "ON"
2. Connect AQS sensor.
3. Measure voltage between terminal "4" and "5" of AQS sensor
Specification : Refer to the specifications.
4. Is the measured voltage within specifications?
YES - Check connectors for looseness, poor connection, bending, corrosion, contamination, deterioration, or damage. Repair or replace as necessary and then go to "Verification of Vehicle Repair" procedure.
NO - Substitute with AQS sensor and check for proper operation.
If the problem is corrected, replace AQS sensor and then 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 "Diagnostic Trouble Codes (DTCs)" mode and then clear DTC.
2. Operate the vehicle and monitor the DTC on the scantool.
3. Are any DTCs present?
YES - Go to the applicable troubleshooting procedure.
NO - System is performing to specification at this time.