DTC P011A

DTC P011A:  Engine Coolant Temperature (ECT) Sensor 1 Circuit Range/Performance Problem

General Description 

Courtesy of HONDA, U.S.A., INC.

Two engine coolant temperature (ECT) sensors and one intake air temperature (IAT) sensor are used by the powertrain control module (PCM). When the engine is stopped and enough time has passed, the temperature of the engine will equalize to ambient temperature. ECT sensor 1 and IAT sensor are compared to ECT sensor 2, and if an inappropriate temperature is read, the PCM detects a malfunction in the corresponding sensor and stores a DTC.

Monitor Execution, Sequence, Duration, DTC Type 

Execution	Once per driving cycle
Sequence	None
Duration	10 seconds or more
DTC Type	Two drive cycles, MIL on

Enable Conditions 

Condition	Minimum	Maximum
Engine off time	6 hours	-

Malfunction Threshold 

A malfunction is detected if the following conditions are present after the engine has stopped and the vehicle condition has been turned to the OFF (LOCK) mode for at least 6 hours before restarting the engine:

Temperature difference between each sensor values		Malfunction judgment
ECT1* - ECT2**	IAT*** - ECT2**	ECT sensor 1	IAT sensor	ECT sensor 2
Higher than 90 deg. F (32 deg. C)	Higher than 90 deg. F (32 deg. C)	Normal	Normal	Failure
	From -11 deg. F (-24 deg. C) to 90 deg. F (32 deg. C)	Failure	Normal	Normal
	Lower than -11 deg. F (-24 deg. C)	Failure	Failure	Normal
From -11 deg. F (-24 deg. C) to 90 deg. F (32 deg. C)	Higher than 90 deg. F (32 deg. C)	Normal	Failure	Normal
	From -11 deg. F (-24 deg. C) to 90 deg. F (32 deg. C)	Normal	Normal	Normal
	From -13 deg. F (-25 deg. C) to -76 deg. F (-60 deg. C)	Normal	Failure	Normal
			Suspended****
	Lower than -76 deg. F (-60 deg. C)	Normal	Failure	Normal
Lower than -11 deg. F (-24 deg. C)	Higher than 90 deg. F (32 deg. C)	Failure	Failure	Normal
	From -11 deg. F (-24 deg. C) to 90 deg. F (32 deg. C)	Failure	Normal	Normal
	Lower than -11 deg. F (-24 deg. C)	Normal	Normal	Failure

*: [ECT SENSOR 1]

**: [ECT SENSOR 2]

***: [IAT SENSOR (1)]

****: Malfunction judgment is suspended because the cooled air introduced after engine start lowers the intake air temperature; the ambient temperature condition does not stay equal.

[ ]: HDS Parameter

Possible Cause 

NOTE:  The causes shown may not be a complete list of all potential problems, and it is possible that there may be other causes.

• ECT sensor 1 failure
• ECT sensor 2 failure
• IAT sensor failure
• Engine block heater attachment (non-genuine part)

Confirmation Procedure 

Operating Condition 

• Turn the vehicle to the OFF (LOCK) mode, and wait at least 6 hours.
• Start the engine, and let it idle for at least 10 seconds.

• Do not use an engine block heater because the engine coolant temperature will not stay equal during engine stop.
• When freeze data is stored, test the vehicle under an ambient temperature close to the intake air temperature in the freeze data.
• When an ambient temperature extremely changes, malfunction judgment may not execute. Avoid extreme temperature changing condition after or before engine start. (When the vehicle is parked in the garage, open the shutter to introduce outside air; then start the engine.)

With the HDS 

None.

Diagnosis Details 

Conditions for setting the DTC 

When a malfunction is detected during the first drive cycle, a Pending DTC is stored in the PCM memory. If the malfunction returns in the next (second) drive cycle, the MIL comes on and a Confirmed DTC and the freeze data are stored.

Conditions for clearing the DTC 

The MIL is cleared if the malfunction does not return in three consecutive trips in which the diagnostic runs. The MIL, the Pending DTC, the Confirmed DTC, and the freeze data can be cleared with the scan tool Clear command or by disconnecting the 12 volt battery.