DTC P2251:00 [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5]

DESCRIPTION	Open circuit between A/F sensor terminal D and PCM terminal 1AB
DETECTION CONDITION	Determination conditions	• The following conditions are met: ― A/F sensor element impedance is specified value or more ― A/F sensor terminal F voltage (B+ terminal) is less than specified value or unstable.
	Preconditions	• Battery voltage: 11—18 V^1 • A/F sensor is activated. • The following DTCs are not detected: ― A/F sensor terminal F voltage (B+ terminal) is less than specified value: • A/F sensor heater: P0031:00, P0032:00 ― A/F sensor terminal F voltage (B+ terminal) is unstable: • Internal PCM malfunction: P064D:00 ^1: Value can be verified by displaying PIDs using M-MDS
	Drive cycle	• 2
	Self test type	• CMDTC self test, KOER self test
	Sensor used	• A/F sensor
FAIL-SAFE FUNCTION	• Not applicable
VEHICLE STATUS WHEN DTCs ARE OUTPUT	• Illuminates check engine light.
POSSIBLE CAUSE	• A/F sensor connector or terminals malfunction • PCM connector or terminals malfunction • Open circuit in wiring harness between A/F sensor terminal D and PCM terminal 1AB • A/F sensor malfunction • PCM malfunction

• If the PCM detects an open circuit in the wiring harness between A/F sensor terminal D and PCM terminal 1AB (COM wiring harness), it stores a DTC. In addition, when there is an open circuit in the wiring harness between A/F sensor terminal D and PCM terminal 1AB (COM wiring harness), the A/F sensor terminal F (B+ terminal) becomes unstable. At this time, the PCM determines an open circuit in the wiring harness (COM wiring harness) between A/F sensor terminal D and PCM terminal 1AB and stores a DTC.

• If the A/F sensor does not activate, monitoring cannot occur because the A/F sensor element has an insulation property which keeps it at a specific temperature range or less.

1. Warm up the engine to allow the engine coolant temperature to reach 80 °C {176 °F} or more.

2. Start the engine and leave it idling for 1 min.

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.

3. 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.

Item	Definition	Unit	Condition/Specification
O2S11	A/F sensor current	µA	• Idle (after warm up): Approx. -39 µA • Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): Approx. 3.84 mA

STEP	INSPECTION	RESULTS	ACTION
1	PURPOSE: VERIFY RELATED SERVICE INFORMATION AVAILABILITY • Verify related Service Information availability. • Is any related Service Information available?	Yes	Perform repair or diagnosis according to the available Service 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	PURPOSE: INSPECT A/F SENSOR CONNECTOR CONDITION • Switch the ignition off. • Disconnect the A/F sensor connector. • Inspect for poor connection (such as damaged/pulled-out pins, corrosion). • Is there any malfunction?	Yes	Replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) Go to the troubleshooting procedure to perform the procedure from Step 1.
3		No	Go to the next step.
4	PURPOSE: INSPECT PCM CONNECTOR CONDITION • Disconnect the PCM connector. • Inspect for poor connection (such as damaged/pulled-out pins, corrosion). • Is there any malfunction?	Yes	Replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) Go to the troubleshooting procedure to perform the procedure from Step 1.
4		No	Go to the next step.
5	PURPOSE: INSPECT A/F SENSOR CIRCUIT FOR OPEN CIRCUIT • Verify that the A/F sensor and PCM connectors are disconnected. • Inspect for continuity between A/F sensor terminal D (wiring harness-side) and PCM terminal 1AB (wiring harness-side). • Is there continuity?	Yes	Go to the next step.
5		No	Refer to the wiring diagram and verify whether or not there is a common connector between A/F sensor terminal D and PCM terminal 1AB. If there is a common connector: • Determine the malfunctioning part by inspecting the common connector and the terminal for corrosion, damage, or pin disconnection, and the common wiring harness for an open circuit. • Repair or replace the malfunctioning part. If there is no common connector: • Repair or replace the wiring harness which has an open circuit. Go to the troubleshooting procedure to perform the procedure from Step 1.
6	PURPOSE: DETERMINE INTEGRITY OF A/F SENSOR • Start the engine and warm it up completely. • Access the O2S11 PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) • Drive the vehicle under the following conditions. Warning • When the M-MDS is used to observe monitor system status while driving, be sure to have another technician with you, or record the data in the M-MDS using the PID/DATA MONITOR AND RECORD capturing function and inspect later. • While performing this step, always operate the vehicle in a safe and lawful manner. ― After increasing the engine speed to 3,000 rpm, decelerate using engine braking. • Is the displayed PID value as follows? ― O2S11: 0.25 mA or more	Yes	Go to the troubleshooting procedure to perform the procedure from Step 1.
6		No	Go to the next step.
7	PURPOSE: INSPECT RELATED SENSOR WIRING HARNESS AND CONNECTOR • Access the O2S11 PID using the M-MDS. (See ON-BOARD DIAGNOSTIC TEST [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) • Does the PID value fluctuate when the PCM and A/F sensor connectors are shaken?	Yes	Inspect the related wiring harness and connector. • Repair or replace the malfunctioning part. Go to the troubleshooting procedure to perform the procedure from Step 1.
7		No	Replace the A/F sensor. (See AIR FUEL RATIO (A/F) SENSOR REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) Go to the troubleshooting procedure to perform the procedure from Step 1.

STEP	INSPECTION	RESULTS	ACTION
1	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 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) • Perform the KOER self test. (See KOEO/KOER SELF TEST [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) • Is the PENDING CODE for this DTC present?	Yes	Repeat the inspection from Step 1. • If the malfunction recurs, replace the PCM. (See PCM REMOVAL/INSTALLATION [SKYACTIV-G 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].) Go to the next step.
1		No	Go to the next step.
2	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 1.5, SKYACTIV-G 2.0, SKYACTIV-G 2.5].)
2		No	DTC troubleshooting completed.