DTC U2021 [ABS (ABS/TCS)]

• The system inhibits torque reduction while the engine coolant temperature is low to protect the engine. After the engine has warmed up, the control returns to normal. (Does not indicate a malfunction)

STEP	INSPECTION	ACTION
1	VERIFY CONDITION OF ENGINE WARMING • Is the engine warmed up?	Yes	Go to the next step.
No	Warm up the engine. • If the TCS OFF light turns off, the system is normal. • If the TCS OFF light remains illuminated, go to the next step.
2	INSPECT FOR OTHER MALFUNCTIONS AFTER ENGINE WARMING • Warm up the engine. • Does the TCS indicator light illuminate and is DTC C1119 output?	Yes	Go to the inspection for DTC C1119. (See DTC C1119 [ABS (ABS/TCS)].)
No	• If the TCS OFF light turns off, the system is normal. • If the TCS OFF light remains illuminated, go to the next step.
3	INSPECT FOR PCM MALFUNCTION • Inspect the PCM DTC using the WDS or equivalent. (See ON-BOARD DIAGNOSTIC TEST [L8, LF, L3].) (See ON‐BOARD DIAGNOSTIC TEST [MZR‐CD (RF Turbo)].) • Are any DTCs output?	Yes	Go to the applicable DTC inspection. (See DTC TABLE [L8, LF, L3].) (See DTC TABLE [MZR‐CD (RF Turbo)].)
No	Go to the next step.
4	INSPECT WATER TEMPERATURE SENSOR FOR MALFUNCTION • Inspect the water temperature sensor. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L8, LF, L3].) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR-CD (RF Turbo)].) • Is the water temperature sensor normal?	Yes	Go to the next step.
No	Replace the water temperature sensor and go to the next step. (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [L8, LF, L3].) (See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)
5	VERIFY THAT SAME DTC IS NOT PRESENT • Clear the DTCs from the memory. (See ABS (ABS/TCS) ON‐BOARD DIAGNOSIS.) • Warm up the engine. • Is the same DTC present?	Yes	Repeat the inspection from Step 1. If the malfunction recurs, replace the ABS/TCS HU/CM. (See ABS (ABS/TCS) HU/CM REMOVAL/INSTALLATION [MTX].) (See ABS (ABS/TCS) HU/CM REMOVAL/INSTALLATION [ATX].)
No	Go to the next step.
6	VERIFY THAT NO OTHER DTCs ARE PRESENT • Are any other DTCs output?	Yes	Go to the applicable DTC inspection. (See ABS (ABS/TCS) ON‐BOARD DIAGNOSIS.)
No	DTC troubleshooting completed.

STEP

INSPECTION

ACTION

VERIFY CONDITION OF ENGINE WARMING

• Is the engine warmed up?

Yes

Go to the next step.

Warm up the engine.

• If the TCS OFF light turns off, the system is normal.

• If the TCS OFF light remains illuminated, go to the next step.

INSPECT FOR OTHER MALFUNCTIONS AFTER ENGINE WARMING

• Warm up the engine.

• Does the TCS indicator light illuminate and is DTC C1119 output?

Yes

Go to the inspection for DTC C1119.

(See DTC C1119 [ABS (ABS/TCS)].)

• If the TCS OFF light turns off, the system is normal.

• If the TCS OFF light remains illuminated, go to the next step.

INSPECT FOR PCM MALFUNCTION

• Inspect the PCM DTC using the WDS or equivalent.

(See ON-BOARD DIAGNOSTIC TEST [L8, LF, L3].)

(See ON‐BOARD DIAGNOSTIC TEST [MZR‐CD (RF Turbo)].)

• Are any DTCs output?

Yes

Go to the applicable DTC inspection.

(See DTC TABLE [L8, LF, L3].)

(See DTC TABLE [MZR‐CD (RF Turbo)].)

Go to the next step.

INSPECT WATER TEMPERATURE SENSOR FOR MALFUNCTION

• Inspect the water temperature sensor.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [L8, LF, L3].)

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR INSPECTION [MZR-CD (RF Turbo)].)

• Is the water temperature sensor normal?

Yes

Go to the next step.

Replace the water temperature sensor and go to the next step.

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [L8, LF, L3].)

(See ENGINE COOLANT TEMPERATURE (ECT) SENSOR REMOVAL/INSTALLATION [MZR-CD (RF Turbo)].)

VERIFY THAT SAME DTC IS NOT PRESENT

• Clear the DTCs from the memory.

(See ABS (ABS/TCS) ON‐BOARD DIAGNOSIS.)

• Warm up the engine.

• Is the same DTC present?

Yes

Repeat the inspection from Step 1.

If the malfunction recurs, replace the ABS/TCS HU/CM.

(See ABS (ABS/TCS) HU/CM REMOVAL/INSTALLATION [MTX].)

(See ABS (ABS/TCS) HU/CM REMOVAL/INSTALLATION [ATX].)

Go to the next step.

VERIFY THAT NO OTHER DTCs ARE PRESENT

• Are any other DTCs output?

Yes

Go to the applicable DTC inspection.

(See ABS (ABS/TCS) ON‐BOARD DIAGNOSIS.)

DTC troubleshooting completed.

DTC	U2021		Engine coolant temperature
DETECTION CONDITION		• Torque reduction inhibited signal (low engine coolant temperature) received from PCM.
POSSIBLE CAUSE		• The system inhibits torque reduction while the engine coolant temperature is low to protect the engine. After the engine has warmed up, the control returns to normal. (Does not indicate a malfunction)

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