NO.15 EMISSION COMPLIANCE [YF (2.0L Zetec)]


15	EMISSION COMPLIANCE
DESCRIPTION	Fails emissions test.
POSSIBLE CAUSE	• Vacuum lines leakage or blockage • Cooling system malfunction • Spark plug malfunction • Leakage from intake manifold • Erratic or no signal from CMP sensor • Inadequate fuel pressure • PCV valve malfunction or incorrect valve installation • EGR valve malfunction • Exhaust system clogging • Fuel tank ventilation system malfunction • Charcoal canister damage • Air cleaner element clogging or restriction • Throttle body malfunction • Erratic signal to ignition coil • Improper air/fuel mixture ratio control operation • Bend or open circuit HO2S wiring harness • Catalyst converter malfunction • Engine internal parts malfunction • Excessive carbon is built up in combustion chamber • Improper engine compression • Improper valve timing Warning The following troubleshooting flow chart contains fuel system diagnosis and repair procedures. Read the following warnings before performing any fuel system-related procedures: • Fuel vapor is hazardous. It can easily ignite, causing serious injury and damage. Always keep sparks and flames away from fuel. • Fuel line spills and leakage are dangerous. Fuel can ignite and cause serious injuries or death and damage. Fuel can also irritate skin and eyes. To prevent this, always complete "BEFORE SERVICE PRECAUTION" and "AFTER SERVICE PRECAUTION" described in this manual. (See BEFORE SERVICE PRECAUTION [YF (2.0L Zetec)].) (See AFTER SERVICE PRECAUTION [YF (2.0L Zetec)].) Caution • Disconnecting/connecting quick release connectors without cleaning them may possibly cause damage to the fuel pipe or quick release connector. Always clean the quick release connector joint area before disconnecting/connecting, and make sure that it is free of foreign material.


STEP	INSPECTION	RESULTS	ACTION
1	Inspect the following: • Vacuum lines for leakage or blockage • Electrical connections • Proper maintenance schedule followed • Intake-air system and air cleaner element concerns: obstructions, leakage, or dirtiness Are all items normal?	Yes	Go to the next step.
1		No	Repair or replace if necessary. Repeat Step 1.
2	Connect the WDS or equivalent to the DLC-2. Retrieve any continuous memory, KOEO and KOER DTCs using the WDS or equivalent. Are any DTCs displayed?	Yes	DTC is displayed: Go to the appropriate DTC inspection. (See DTC TABLE [YF (2.0L Zetec)].)
2		No	No DTC is displayed: Go to the next step.
3	Is any other driveability concern present?	Yes	Go to the appropriate symptom troubleshooting.
3	Is any other driveability concern present?	No	Go to the next step.
4	Connect the WDS or equivalent to the DLC-2. Access the ECT PID. Warm up the engine and idle it. Verify that the ECT PID is correct. (See PCM INSPECTION [YF (2.0L Zetec)].) Is the ECT PID correct?	Yes	Go to the next step.
4		No	Inspect for coolant leakage, cooling fan and thermostat operation.
5	Connect the WDS or equivalent to the DLC-2. Warm up the engine and idle it. Access the O2S11 PID. Is the O2S11 PID normal? • More than 0.45 V when the accelerator pedal is suddenly depressed: rich condition. • Less than 0.45 V during fuel cut: lean condition.	Yes	Go to the next step.
5		No	Inspect and repair or replace the front HO2S, wiring harness, connector or terminal, then go to the next step. (See HEATED OXYGEN SENSOR (HO2S) INSPECTION [YF (2.0L Zetec)].)
6	Perform the spark test. (See Spark Test.) Is a strong blue spark visible at each cylinder?	Yes	Go to the next step.
6		No	Repair or replace the malfunctioning part according to spark test result.
7	Install a fuel pressure gauge to the fuel line. Start the engine and idle it. Measure the fuel line pressure during idle. Is the fuel line pressure correct during idle? (See FUEL LINE PRESSURE INSPECTION [YF (2.0L Zetec)].)	Yes	Go to the next step.
7		No	Low: Inspect the fuel line for clogging. • If normal, replace fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [YF (2.0L Zetec)].) High: Replace the fuel pump unit. (See FUEL PUMP UNIT REMOVAL/INSTALLATION [YF (2.0L Zetec)].)
8	Remove and shake the PCV valve. Does the PCV valve rattle?	Yes	Go to the next step.
8	Remove and shake the PCV valve. Does the PCV valve rattle?	No	Replace the PCV valve.
9	Inspect for fuel saturation inside the charcoal canister. Is an excess amount of liquid fuel present in canister?	Yes	Replace the charcoal canister.
9		No	Inspect the fuel tank vent system. Then, go to the next step.
10	Visually inspect the exhaust system part. Is there any deformed exhaust system part?	Yes	Replace the part.
10		No	Go to the next step.
11	Inspect the threeway catalytic converter. (See EXHAUST SYSTEM INSPECTION [YF (2.0L Zetec)].) Is the threeway catalytic converter normal?	Yes	Inspect the EGR system. (See EGR System Operation Inspection.)
11		No	Replace the threeway catalytic converter.
12	Verify test results. • If normal, return to the diagnostic index to service any additional symptoms. (See ENGINE SYMPTOM TROUBLESHOOTING [YF (2.0L Zetec)].) • If any malfunction remains, inspect related service information and, repair or diagnosis accordingly. - If the vehicle is repaired, troubleshooting completed. - If the vehicle is not repaired or additional diagnostic information is not available, replace the PCM. (See PCM REMOVAL/INSTALLATION [YF (2.0L Zetec)].)