Damaged, chafed or corroded wiring to the oil pressure control solenoid (open circuit or short to earth or supply); Poor connection at the solenoid or control unit plug (corrosion, bent or loose pins, water ingress); Faulty oil pressure control solenoid (open or shorted coil, or wrong resistance); Oil leaking along the harness into the connector, damaging the terminals or insulation; Low or contaminated oil or fluid affecting the solenoid and its operation; Low battery voltage or a poor earth causing incorrect circuit readings; Faulty control unit driver circuit.

P1689

Oil Pressure Control Solenoid Circuit Malfunction.

Other
Powertrain
Manufacturer code
Medium severity

How this code is built

P: SystemPowertrain
1: Defined byThe manufacturer
6: AreaComputer and output circuits
89: FaultThe specific fault in that area

What it means

P1689 is a manufacturer-specific code that, for the make and listing here, means the control unit has detected a fault in the oil pressure control solenoid circuit. The control unit saw an electrical reading from the solenoid circuit (open circuit, short, or a value outside the expected range) that did not match what it commanded. Which system the solenoid belongs to, such as engine oil pressure control or transmission line pressure, depends on the make, model and engine. Other manufacturers use P1689 for different faults, so confirm the definition for the exact vehicle.

Symptoms

Warning light on (engine management and possibly an oil pressure or gearbox warning, depending on the model)
Car may enter a fail-safe or limp mode with reduced performance
Harsh, delayed or flared gear changes if the solenoid is part of an automatic transmission
Low or erratic oil pressure warning or reading, if the solenoid controls engine oil pressure
Poor engine response or rough running on some models
Fault returns soon after being cleared

Possible causes

Damaged, chafed or corroded wiring to the oil pressure control solenoid (open circuit or short to earth or supply)likely
Poor connection at the solenoid or control unit plug (corrosion, bent or loose pins, water ingress)likely
Faulty oil pressure control solenoid (open or shorted coil, or wrong resistance)likely
Oil leaking along the harness into the connector, damaging the terminals or insulationpossible
Low or contaminated oil or fluid affecting the solenoid and its operationpossible
Low battery voltage or a poor earth causing incorrect circuit readingspossible
Faulty control unit driver circuitrare

How to diagnose

Confirm the code definition for the exact make, model and engine, and read the freeze frame data to see when the fault set.
Check for other stored codes, especially battery voltage, oil pressure, transmission or communication faults, and deal with those first.
Check the oil level and condition (or transmission fluid level and condition, if the solenoid is in the gearbox) against the manufacturer's specification.
Visually inspect the solenoid wiring and connectors for chafing, heat damage, oil contamination, corrosion and bent or pushed-back pins.
Measure battery voltage and check the relevant supply and earth connections for the solenoid circuit.
Measure the solenoid coil resistance and compare it with the manufacturer's figure for that model.
With the circuit tested, check the wiring between the solenoid and control unit for continuity and for shorts to earth or supply.
Command the solenoid with diagnostic equipment, if supported, and check that it responds and that actual pressure follows the request.

How to fix

Repair or replace damaged wiring and fix any chafing points, following the manufacturer's wiring information.
Clean or replace corroded or damaged connectors and terminals, and ensure they are properly seated and sealed.
Replace the oil pressure control solenoid if its resistance or operation is out of specification.
Correct the oil or fluid level and condition, and cure any leak that is contaminating the harness or connector.
Restore a good battery condition and repair poor earth connections.
Only after all other causes are ruled out, diagnose the control unit and repair or replace it, including any required programming.

Can I keep driving?

Medium severity

Short, gentle journeys may be possible, but the car could be in a reduced-performance mode and a genuine oil pressure or gearbox problem could cause damage. Get it checked soon, and stop driving if an oil pressure warning shows or the gearbox behaves abnormally.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.