Failed wastegate solenoid (sticking, open, or shorted coil); Damaged or disconnected wiring harness to the solenoid; Corroded or loose electrical connector at the solenoid; Vacuum or boost hose leak between the solenoid and wastegate actuator; Faulty PCM driver circuit (less common); Restricted solenoid filter or debris blocking the valve

DTC codes / Mazda codes / P1690

P1690 · MazdaWastegate Solenoid Circuit

Q: What does code P1690 mean?

Wastegate Solenoid Circuit. P1690 on Mazda vehicles indicates that the powertrain control module (PCM) has detected an electrical fault in the wastegate solenoid circuit, which controls boost pressure on turbocharged engines. The PCM monitors the solenoid's command and feedback circuits and sets this code when the measured current or voltage falls outside the expected range for the commanded state.

P1690 on Mazda vehicles indicates that the powertrain control module (PCM) has detected an electrical fault in the wastegate solenoid circuit, which controls boost pressure on turbocharged engines. The PCM monitors the solenoid's command and feedback circuits and sets this code when the measured current or voltage falls outside the expected range for the commanded state.

SystemPowertrain

Code typeMazda specific

SeverityMedium

Fix difficultyIntermediate

AreaComputer and output circuits

Symptoms you may notice

Check engine light illuminated, often with no other noticeable symptoms
Reduced engine power or limp mode, especially under acceleration
Overboost or underboost conditions leading to sluggish performance
Poor fuel economy or increased turbo lag
In rare cases, the engine may enter a fail-safe mode limiting boost

Common causes, most likely first

Failed wastegate solenoid (sticking, open, or shorted coil)
Damaged or disconnected wiring harness to the solenoid
Corroded or loose electrical connector at the solenoid
Vacuum or boost hose leak between the solenoid and wastegate actuator
Faulty PCM driver circuit (less common)
Restricted solenoid filter or debris blocking the valve

How to diagnose and fix it

Inspect the wastegate solenoid connector and wiring for corrosion, damage, or looseness
Check vacuum/boost hoses for cracks, leaks, or disconnections
Measure solenoid resistance and compare to factory specification
Test solenoid operation with a scan tool bidirectional control or apply 12V to verify clicking
Check for power and ground signals at the solenoid connector with a multimeter
If wiring and solenoid test good, diagnose PCM driver circuit or replace PCM as last resort
Clear codes and perform a road test to verify repair

Wastegate Solenoid Diagnostics Beyond the Code

A stuck-open wastegate solenoid often causes overboost and a P0234 code, but P1690 can set first due to electrical monitoring.
Mazda's wastegate solenoid is duty-cycle controlled; a solenoid that tests good statically may fail under heat or vibration.
Vacuum leaks at the wastegate actuator or solenoid can mimic solenoid failure, so always pressure-test the circuit.
Some technicians replace the turbocharger unnecessarily when the fault is a $5 hose or corroded connector.
P1690 can be intermittent; a wiggle test of the harness while monitoring solenoid command often reveals the issue.

Can I keep driving with P1690?

You can drive the vehicle with P1690, but avoid heavy acceleration and sustained boost to prevent potential engine damage from overboost or limp mode. Have the fault diagnosed promptly to restore proper turbo operation.

Tools that help

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Guidance is general and written for Mazda vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.