DTC P0126:00 [SKYACTIV-G 2.5]

< Previous Next >

2014 - Mazda6 - Engine

DTC P0126:00 [SKYACTIV-G 2.5]

NOTE:

To determine the malfunctioning part, proceed with the diagnostics from "Function Inspection Using M-MDS".

Details On DTCs


DESCRIPTION	Thermostat stuck open
DETECTION CONDITION	Determination conditions	Actual engine coolant temperature does not exceed 71 °C {160 °F} even though the estimated engine coolant temperature after the engine is started exceeds 71 °C {160 °F}.
	Preconditions	Engine coolant temperature at engine start: 52 °C {126 °F} or less^1 IAT: −10—45 °C {14—113 °F}^1 Vehicle speed: 140 km/h {87 mph} or less^1 Engine speed: 5,400 rpm or less^1 Idle ratio: 50 % or less The following DTCs are not detected: Fuel system malfunction: P0171:00, P0172:00, P2096:00, P2097:00 ECT sensor No.1 malfunction: P0117:00, P0118:00 MAF sensor malfunction: P0102:00, P0103:00 ^*1: Value can be verified by displaying PIDs using M-MDS
	Drive cycle	2
	Self test type	CMDTC self test
	Sensor used	Desired engine coolant temperature: intake air temperature (IAT sensor), engine speed (CKP sensor), charging efficiency Actual engine coolant temperature: ECT sensor No.1, ECT sensor No.2
FAIL-SAFE FUNCTION	Not applicable
VEHICLE STATUS WHEN DTCs ARE OUTPUT	Illuminates check engine light. Heating is ineffective after engine is started
POSSIBLE CAUSE	ECT sensor No.1 malfunction ECT sensor No.2 malfunction Poor assembly of ECT sensor No.1 Poor assembly of ECT sensor No.2 Poor assembly of engine coolant hose (engine coolant passage malfunction) Poor engine coolant, leakage, or freezing Use of unspecified engine coolant Foreign matter caught in thermostat (foreign matter penetration in engine coolant) Thermostat malfunction PCM malfunction

System Wiring Diagram

Not applicable

Function Explanation (DTC Detection Outline)

The PCM calculates the estimated engine coolant temperature according to the engine speed, charging efficiency, and intake air temperature. If the actual engine coolant temperature does not exceed 71.1 °C {160 ° F} during the malfunction determination time after the estimated engine coolant temperature exceeds 71.1 °C {160 °F}, malfunction determination for the engine coolant system is performed and a DTC is stored.

The malfunction determination time varies depending on the engine speed, charging efficiency, and intake air temperature.

Repeatability Verification Procedure

Switch the ignition off.

Leave the vehicle until the engine coolant temperature reaches approx. 35 °C {95 °F}.

Start the engine.

NOTE:

Match the engine coolant temperature in the recorded FREEZE FRAME DATA (Mode 2)/snapshot data, the vehicle speed, and engine speed values to the best extent possible while driving the vehicle.

Try to reproduce the malfunction by driving the vehicle for 5 min based on the values in the FREEZE FRAME DATA (Mode 2)/snapshot data.

PID Item/Simulation Item Used In Diagnosis

PID/DATA monitor item table


Item	Definition	Unit	Condition/Specification
ECT	Engine coolant temperature No.1	°C, °F	Displays ECT
ECT	Engine coolant temperature No.1	V	ECT is 20 °C {68 °F}: Approx. 3.10 V ECT is 40 °C {104 °F}: Approx. 2.16 V ECT is 60 °C {140 °F}: Approx. 1.40 V ECT is 80 °C {176 °F}: Approx. 0.87 V ECT is 100 °C {212 °F}: Approx. 0.54 V

Function Inspection Using M-MDS


STEP	INSPECTION	RESULTS	ACTION
1	PURPOSE: VERIFY RELATED REPAIR INFORMATION AVAILABILITY Verify related Service Bulletins and/or on-line repair information availability. Is any related repair information available?	Yes	Perform repair or diagnosis according to the available repair information. If the vehicle is not repaired, go to the next step.
1		No	Go to the next step.
2	PURPOSE: RECORD VEHICLE STATUS AT TIME OF DTC DETECTION TO UTILIZE WITH REPEATABILITY VERIFICATION Has the FREEZE FRAME DATA (Mode 2)/snapshot data been recorded?	Yes	Go to the next step.
2		No	Record the FREEZE FRAME DATA (Mode 2)/snapshot data on the repair order, then go to the next step. NOTE: Recording can be facilitated using the screen capture function of the PC.
3	DETERMINE IF MALFUNCTION CAUSE IS ECT SENSOR NO.1 (PCM INPUT SIGNAL) OR OTHER PART Switch the ignition off, then ON (engine off). Perform the Pending Trouble Code Access Procedure and DTC Reading Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].) Is the PENDING CODE/DTC P0116:00 also present?	Yes	Inspect for DTC P0116:00 due to the high possibility of an ECT sensor No.1 malfunction. (See DTC P0116:00 [SKYACTIV-G 2.5].)
3		No	Go to the troubleshooting procedure to perform the procedure from Step 1.

Troubleshooting Diagnostic Procedure

Intention of troubleshooting procedure

Step 1—2

Perform an engine coolant-related inspection.

Step 3

Perform an engine coolant passage assembly condition-related inspection.

Step 4

Perform a unit inspection of the thermostat.

Step 5—6

Perform a PCM input signal part-related inspection.

Step 7—8

Verify that the primary malfunction is resolved and there are no other malfunctions.


STEP	INSPECTION	RESULTS	ACTION
1	PURPOSE: DETERMINE IF ENGINE COOLANT USED AFFECTS CONDITION BY VERIFYING WITH CUSTOMER AND INSPECTING COLOR, ODOR, AND FOAMING DUE TO POSSIBILITY OF ENGINE COOLANT FREEZING IF ENGINE COOLANT CONCENTRATION IS LOW Is the specified engine coolant being used?	Yes	Go to the next step.
1		No	Replace the engine coolant, then go to Step 7. (Advise the customer to use specified engine coolant used.) (See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.5].)
2	PURPOSE: VERIFY THAT THERE IS NO ENGINE COOLANT LEAKAGE OR FOREIGN MATTER PENETRATION BECAUSE ECT SENSOR MAY NOT MEASURE CORRECT TEMPERATURE DUE TO ENGINE COOLANT LEAKAGE Perform the "ENGINE COOLANT LEAKAGE INSPECTION". (See ENGINE COOLANT LEAKAGE INSPECTION [SKYACTIV-G 2.5].) Is there engine coolant leakage or foreign matter penetration?	Yes	If there is engine coolant leakage: Repair or replace the malfunctioning location and refill the system with engine coolant. If there is foreign matter penetration: Replace engine coolant after removing the foreign matter. (See ENGINE COOLANT REPLACEMENT [SKYACTIV-G 2.5].) Go to Step 7.
2		No	Go to the next step.
3	PURPOSE: VERIFY IF ENGINE COOLANT PASSAGE IS CORRECT BECAUSE CORRECT ENGINE COOLANT TEMPERATURE CANNOT BE DETERMINED IF ENGINE COOLANT PASSAGE IS INCORRECT Is the engine coolant passage (such as hose) connected correctly? (ask customer if engine coolant passage has been serviced somewhere other than Authorized Mazda Dealer)	Yes	Go to the next step.
3		No	Connect engine coolant passage correctly, then go to Step 7.
4	PURPOSE: EXAMINE THERMOSTAT BECAUSE ENGINE COOLANT TEMPERATURE INCREASE SLOWS IF THERMOSTAT IS STUCK OPEN Inspect the thermostat. (See THERMOSTAT INSPECTION [SKYACTIV-G 2.5].) Is there any malfunction?	Yes	Replace the thermostat, then go to Step 7. (See THERMOSTAT REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)
4		No	Go to the next step.
5	PURPOSE: EXAMINE ECT SENSOR BECAUSE ENGINE COOLANT TEMPERATURE CANNOT BE MEASURED CORRECTLY IF ECT SENSOR IS MALFUNCTIONING Inspect the ECT sensor No.1 and ECT sensor No.2. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [SKYACTIV-G 2.5].) Is there any malfunction?	Yes	Replace the ECT sensor No.1 or ECT sensor No.2, then go to Step 7. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)
5		No	Go to the next step.
6	PURPOSE: VERIFY ASSEMBLY CONDITION BECAUSE ENGINE COOLANT TEMPERATURE CANNOT BE MEASURED CORRECTLY IF ECT SENSOR IS NOT ASSEMBLED CORRECTLY Verify the ECT sensor No.1 and ECT sensor No.2 assembly conditions. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5].) Are the ECT sensor No.1 and ECT sensor No.2 assembled correctly?	Yes	Go to the next step.
6		No	Assemble the ECT sensor No.1 and ECT sensor No.2 correctly, then go to the next step. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 2.5].)
7	PURPOSE: VERIFICATION OF VEHICLE REPAIR COMPLETION Always reconnect all disconnected connectors. Clear the DTC from the PCM memory using the M-MDS. (See CLEARING DTC [SKYACTIV-G 2.5].) Implement the repeatability verification procedure. (See Repeatability Verification Procedure.) Perform the Pending Trouble Code Access Procedure. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 2.5].) Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1 of the troubleshooting diagnostic procedure. If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 2.5].) Go to the next step.
7		No	Go to the next step.
8	PURPOSE: VERIFY IF THERE IS ANY OTHER MALFUNCTION Is any other DTC or pending code stored?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [SKYACTIV-G 2.5].)
8		No	DTC troubleshooting completed.

< Previous Next >