Archives: DTC Codes

What Does Code P1632 Mean? DTC P1632 indicates a malfunction within the “smart alternator” control circuit or its associated sensor feedback loop. In modern vehicles, the Engine Control Module (ECM) or Powertrain Control Module (PCM) actively manages the alternator’s output voltage and current based on various factors such as electrical load, battery state of charge, […]

What Does Code P1633 Mean? The diagnostic trouble code P1633 indicates that the Powertrain Control Module (PCM), also commonly referred to as the Engine Control Module (ECM), has detected an abnormally low voltage supply to its Keep Alive Memory (KAM) circuit. The KAM is a dedicated, non-volatile memory bank within the PCM that retains critical […]

What Does Code P1634 Mean? The diagnostic trouble code P1634, often described as “Data Output Link Circuit Failure,” indicates that the Powertrain Control Module (PCM) or Engine Control Module (ECM) has detected an anomaly in the electrical circuit integrity or communication on a specific data output link. This particular circuit is crucial for the PCM […]

What Does Code P1635 Mean? DTC P1635 signifies that the Powertrain Control Module (PCM), or in some architectures, the Engine Control Module (ECM) in conjunction with other modules like the Anti-lock Brake System (ABS) module, has detected an inconsistency in the calculated tire/axle ratio that falls outside of its acceptable programmed range. This code is […]

What Does Code P1636 Mean? DTC P1636 signifies an Inductive Signature Chip Communication Error within the vehicle’s diagnostic system. This code is most commonly associated with proprietary anti-theft or immobilizer systems, such as Ford’s Passive Anti-Theft System (PATS). The Engine Control Module (ECM), often referred to as the Powertrain Control Module (PCM), expects to receive […]

What Does Code P1637 Mean? The OBD-II diagnostic trouble code P1637 indicates a malfunction within the Controller Area Network (CAN) communication link between the Engine Control Module (ECM), also known as the Powertrain Control Module (PCM), and the Anti-lock Brake System Control Module (ABSCM). Specifically, the ECM/PCM has detected that it is not receiving expected […]

What Does Code P1638 Mean? The diagnostic trouble code P1638 signifies a “CAN Link ECM/INSTM Circuit / Network Malfunction.” This code is set when the Engine Control Module (ECM), also commonly referred to as the Powertrain Control Module (PCM), detects an irregularity in the Controller Area Network (CAN) communication bus specifically involving the Instrument Cluster […]

What Does Code P1639 Mean? DTC P1639 indicates that the Powertrain Control Module (PCM), or in some applications the Engine Control Module (ECM), has detected an issue with its internal Vehicle Identification Block. This block is a dedicated section of non-volatile memory (e.g., EEPROM or Flash memory) within the control unit that stores critical vehicle-specific […]

What Does Code P1640 Mean? The diagnostic trouble code (DTC) P1640, “Powertrain DTCs Available in Another Module,” is an informational code set by the Powertrain Control Module (PCM), often synonymous with the Engine Control Module (ECM). Unlike most DTCs which indicate a specific fault within the PCM’s directly monitored circuits or systems, P1640 signifies that […]

What Does Code P1641 Mean? DTC P1641 signifies a malfunction detected by the Engine Control Module (ECM), also commonly referred to as the Powertrain Control Module (PCM), within the primary circuit responsible for powering the fuel pump. This code indicates that the ECM has observed an electrical characteristic that falls outside of its predefined operational […]