PowertrainP1978
CautionSeverity: Caution - get it checked when you can
PTC high voltage undervoltage fault
Key terms: Control module: a small computer that runs one part of the car · Powertrain: engine, transmission and emissions
1What it means in plain English
The engine or powertrain control system has stored a fault that does not have specific guidance in this database yet.
2Common causes
- Sensor or actuator fault
- Wiring or connector fault
- Vacuum or intake leak
- Fuel or ignition problem
- Control module fault
3Can I drive?
Have it diagnosed promptly. If the car runs and drives normally, drive gently to a workshop. If it runs badly, stalls, overheats, loses oil pressure, or a warning light is flashing or red, stop safely and get professional help. If the code concerns the brakes, brake vacuum or brake assist, do not drive until it is checked: a hard pedal or longer stopping distance means stop.
This page gives general information. It is not professional advice. For a definite diagnosis and a repair quote, ask a qualified mechanic to inspect the car.
4Brand data 15
| Brand | Code | Description | System |
|---|---|---|---|
| BAIC Motor | P1978 | PTC high voltage undervoltage fault Brand | Powertrain |
| Chery | P1978 | Secondary Air Injection Valve 4 (N385): Electrical Malfunction Brand | Powertrain |
| Daewoo | P1978 | No description available | Powertrain |
| DFXK | P1978 | Secondary Air Injection Valve 4 (N385): Electrical Malfunction Brand | Powertrain |
| EOBD | P1978 | Học ly hợp Brand | Powertrain |
| Geely | P1978 | Secondary Air Injection Valve 4 (N385): Electrical Malfunction Brand | Powertrain |
| GM | P1978 | No description available | Powertrain |
| Holden | P1978 | No description available | Powertrain |
| Isuzu | P1978 | No description available | Powertrain |
| Mitsubishi | P1978 | ETV IPD HI SHT./LO SHT./Overheat Brand | Powertrain |
| Opel | P1978 | No description available | Powertrain |
| Peugeot | P1978 | No description available | Powertrain |
| Proton | P1978 | ETV IPD HI SHT./LO SHT./Overheat Brand | Powertrain |
| Saab | P1978 | No description available | Powertrain |
| Smart | P1978 | No description available | Powertrain |
Legend: SAE is the generic J2012 description; Brand is text taken from that manufacturer’s data. Manufacturer rows keep the wording and language of the source data, and non-English text is tagged so screen readers pronounce it correctly.
5Related codes
Browse Pxxx codes or P197xx codes.