HF: Catalyst Efficiency Monitor And Exhaust — 2016 workshop reference 5158

Vehicle applicability: This diagnostic supplement covers multiple Ford vehicles and engines. Follow the application named in the source below. Some references apply to vehicles other than Mustang.

power, loss of power, or no start), REFER to Section 3 , Symptom Charts.

HF9 CHECK MANIFOLD VACUUM FOR AN INDICATION OF EXCESSIVE EXHAUST SYSTEM RESTRICTION

Note: When the engine is first started and is idled, the reading may be normal 51-74 kPa (15-22 in-Hg), but as the engine RPM is increased, the back pressure caused by a clogged exhaust system causes the needle to slowly drop to 0 kPa (0 in-Hg). The needle then may slowly rise. Excessive exhaust restriction causes the needle to drop to a low point even if the engine is only idling.

• Attach a vacuum gauge to the intake manifold vacuum source.

• Observe the vacuum gauge while increasing the engine RPM.

Does the vacuum gauge indicate an exhaust restriction concern?

Yes	No
REPAIR as necessary. Clear the PCM DTCs. REPEAT the self-test. To continue diagnosis of a symptom (lack of power, loss of power, or no start), REFER to Section 3 , Symptom Charts.	No indication of restrictions or leaks has been detected in the exhaust system. To continue diagnosis of a symptom (lack of power, loss of power, or no start), REFER to Section 3 , Symptom Charts.

Yes

REPAIR as necessary.

Clear the PCM DTCs. REPEAT the self-test.

To continue diagnosis of a symptom (lack of power, loss of power, or no start), REFER to Section 3 , Symptom Charts.

No indication of restrictions or leaks has been detected in the exhaust system.

To continue diagnosis of a symptom (lack of power, loss of power, or no start), REFER to Section 3 , Symptom Charts.

HF10 CARRY OUT THE CATALYST MONITOR DRIVE CYCLE

• Carry out the catalyst monitor drive cycle. Refer to Section 2, On Board Diagnostic (OBD) Drive Cycle.

• Carry out the PCM self-test.

Are DTCs P0420 or P0430 present?

Yes	No
INSTALL a new catalyst between the monitored HO2S, only for the bank referenced, (P0420 Bank 1), (P0430 Bank 2). Do not install a new unmonitored catalyst unless it is repaired as an assembly. REFER to the Workshop Manual Section 309-00, Exhaust System. Clear the PCM DTCs. REPEAT the self-test.	The test is complete and no concerns are present.

Yes

INSTALL a new catalyst between the monitored HO2S, only for the bank referenced, (P0420 Bank 1), (P0430 Bank 2). Do not install a new unmonitored catalyst unless it is repaired as an assembly. REFER to the Workshop Manual Section 309-00, Exhaust System.

Clear the PCM DTCs. REPEAT the self-test.

The test is complete and no concerns are present.

Source reference 5158

2016 Mustang workshop publication supplied to Mustang Atlas. Original technical text and illustrations; HTML formatting by Mustang Atlas. Source page numbering is retained for traceability. Follow the configuration, revision, warnings, and cross-references in the material. About this edition.