P0694 Code: ECM/PCM Power Relay Circuit (P0694)
Note: We do not currently have verified model-specific diagnostic data for the Lexus Lx. The symptoms and fixes listed below are the standard generic OBD2 guidelines for the P0694 code. Always consult a factory service manual before replacing parts.
What does this mean?
Code P0694 indicates a problem with the ECM/PCM power relay circuit.
Diagnostic system: Control module, power, and communication
On a Lexus Lx, the P0694 code should be diagnosed as part of the control module, power, and communication group. Related codes and live data from this same system can change the repair priority, so avoid replacing parts from the code name alone.
Most Common Causes for Lexus Lx
- Internal PCM/ECM failure
- Damaged, chafed, or broken wiring harness
- Weak or failing battery
- Corroded or loose electrical connector
Symptoms to Watch For
- Check Engine Light is illuminated
- Engine cranks but won't start
- Engine stalling or dying unexpectedly
- Vehicle enters reduced power / limp mode
Before replacing parts, check these first
- Check battery health, charging voltage, fuses, grounds, and module connectors.
- Look for network communication codes and multiple-module failures.
- Confirm power and ground before suspecting a failed PCM/ECM/TCM.
- Check for blown fuses, weak battery voltage, and damaged connectors before buying major parts.
Live data to compare
- Battery voltage while cranking
- Module power and ground voltage drop
- Network communication codes
How to Diagnose
Common Mistakes
Replacing a control module before checking voltage supply, grounds, fuses, water intrusion, and connector condition. Always confirm the fault with freeze-frame data, live data, visual inspection, and circuit checks before spending money on parts.
Repair verification
After the repair, clear P0694, complete a drive cycle, and confirm the monitor runs without the code returning. Save the before/after scan report if the vehicle needs emissions inspection.
Frequently Asked Questions
Can I drive with the P0694 code?
If the check engine light is solid, you can usually drive to a safe location or mechanic. If the light is flashing, pull over immediately to prevent catastrophic engine or catalytic converter damage.
Will the P0694 code clear itself?
Once the underlying problem is fixed, the engine computer will run its self-checks. If it passes over several drive cycles, the light will turn off automatically. You can also clear it immediately using an OBD2 scanner.
Will this code fail an emissions test?
Yes. If the Check Engine Light is on due to the P0694 code, your Lexus will automatically fail an OBD2 plug-in emissions or smog test.
What should I check first for P0694?
Check battery health, charging voltage, fuses, grounds, and module connectors. Look for network communication codes and multiple-module failures. Confirm power and ground before suspecting a failed PCM/ECM/TCM.
Join the Discussion
Repair Estimate
Fuse, connector, wiring, cleaning, or basic inspection
Control module replacement and programming after power/ground verification
Includes parts and labor. May vary by location.
Power and ground repairs are often cheaper than module replacement, which may also require programming.
DIY Difficulty
Can usually be performed at home with basic hand tools.