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.
Powertrain DTC Charts and Descriptions 4-113
Diagnostic Trouble Code (DTC) Charts and Descriptions
P1639 - Vehicle ID (VID) Block Corrupted, Not Programmed
Description: This DTC sets when the VID block is not programmed or the information within is corrupt.
Possible Causes: • New PCM
• Incorrect PCM
• Incorrect VID configuration
Diagnostic Aids: Program the PCM to the most recent calibration available.
The VID block must be programmed. Refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM), Making Changes to the VID Block.
Application Key On Engine Off Key On Engine Running Continuous Memory
All Refer to the Description, Possible Causes and Diagnostic Aids for the DTC.
P1646 - Linear O2 Sensor Control Chip (Bank 1)
Description: The PCM monitors the application specific integrated circuit that controls and monitors the universal heated
oxygen sensor bank 1, sensor 1 (HO2S11). This DTC sets when the PCM detects an internal circuit or communication concern.
Possible Causes: • Damaged universal HO2S11 wiring
• Damaged PCM
Diagnostic Aids: Check for other DTCs and diagnose those first. Check for intermittent universal HO2S wiring concerns. Check
the universal HO2S wiring between the PCM and the sensor for damage. Check for aftermarket performance products. Reprogram or update the calibration. Clear the DTCs, repeat the self-test. If the DTC is retrieved again, install a new PCM. Refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM).
Application Key On Engine Off Key On Engine Running Continuous Memory
All Refer to the Description, Possible Causes and Diagnostic Aids for the DTC.
P1647 - Linear O2 Sensor Control Chip (Bank 2)
Description: The PCM monitors the application specific integrated circuit that controls and monitors the universal heated
oxygen sensor bank 2, sensor 1 (HO2S21). This DTC sets when the PCM detects an internal circuit or communication concern.
Possible Causes: • Damaged universal HO2S21 wiring
• Damaged PCM
Diagnostic Aids: Check for other DTCs and diagnose those first. Check for intermittent universal HO2S wiring concerns. Check
the universal HO2S wiring between the PCM and the sensor for damage. Check for aftermarket performance products. Reprogram or update the calibration. Clear the DTCs, repeat the self-test. If the DTC is retrieved again, install a new PCM. Refer to Section 2, Flash Electrically Erasable Programmable Read Only Memory (EEPROM).
Application Key On Engine Off Key On Engine Running Continuous Memory
All Refer to the Description, Possible Causes and Diagnostic Aids for the DTC.
P164A - O2 Sensor Positive Current Trim Circuit Performance (Bank 1 Sensor 1)
Description: A resistor is installed in the universal heated oxygen sensor bank 1, sensor 1 (HO2S11) connector for part to
part variance. The PCM determines the value of this resistor by taking multiple measurements of the resistor during each ignition ON event. The PCM uses this value to compensate for the variance in the pumping current signal. This DTC sets when the PCM receives an inconsistent or erratic measurement of the resistor.
Possible Causes: • Corrosion
• Incorrect connections
• Damaged universal HO2S11
Diagnostic Aids:
Application Key On Engine Off Key On Engine Running Continuous Memory
All GO to Pinpoint Test DZ.
2016 Powertrain Control/Emissions Diagnosis, Gasoline Engines, 3/2015
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.