What does it mean?
P1670 is a Powertrain (engine, transmission, fuel system) fault code. It indicates: Output Driver 4 Input Voltage High Input .
Symptoms
- MIL on, usually with companion codes naming the specific device on that driver group
- The affected relay, solenoid or lamp does not operate at all
- Erratic accessory operation, or a device that works intermittently
- Depending on the output involved, a lost cooling fan, EVAP or lamp function
- In some cases reduced power or a limp-mode strategy if the output matters to engine control
Likely causes
- Open circuit in the controlled device, so the feedback line stays pulled up
- Relay coil or solenoid on that driver group open internally
- Corroded connector or backed-out pin at the controlled device
- Control wire shorted to battery positive
- Blown fuse leaving the load unpowered on the supply side
- Poor ground for the controlled component
- Failed low-side driver inside the control module
How to fix it
- Record all stored codes; the companion codes identify which output belongs to driver group 4
- Unplug the suspect device and measure its coil resistance against specification; an open coil produces exactly this fault
- With the ignition on, check for battery voltage on the supply side of the device connector and check the related fuse
- Back-probe the control wire while commanding the output with the scan tool and watch whether the voltage pulls down
- Test the control wire for an open circuit and for a short to battery positive
- Inspect the module and device connectors for corrosion, spread terminals and pushed-out pins
- Repair the open circuit and retest; replace the module only when the external circuit is proven good