ECM/PCM Power Relay Sense Circuit Low
The P0689 code means the vehicle's onboard diagnostic system has detected: ECM/PCM Power Relay Sense Circuit Low. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $100 - $800 (parts and labor)
Best-selling code reader on Amazon. Reads and clears check engine codes on any 1996+ vehicle. Under $30.
Essential for diagnosing sensor codes, checking voltage, and testing circuits. Under $15 and pays for itself on the first job.
Affiliate links — we earn a commission at no extra cost to you.
Common Symptoms
- Check Engine Light on
- ECM senses low relay feedback
- Vehicle may enter limp mode
- Possible no-start condition
Probable Causes (Ranked by Likelihood)
- Short to ground in relay sense circuit Very High
- Wiring damage or corrosion in the circuit High
- Poor electrical connection at module or component Moderate
- ECM or control module internal failure Low
Frequently Asked Questions
What does P0689 mean?
P0689 indicates a fault in the ecm/pcm power relay sense circuit low. This is an electronic control system code that affects the ECM's ability to manage the associated component or system.
Is P0689 a serious code?
Yes, this code indicates a critical control circuit issue that can affect vehicle operation and should be addressed immediately.
Can a low battery cause ECM-related codes?
Yes. Low battery voltage can cause various ECM and module communication codes. Always verify the battery is fully charged and the charging system is working before diagnosing electronic control module codes.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
-
Use a scan tool to read data related to ECM/PCM Power Relay Sense
-
Inspect all related wiring, connectors, and grounds for damage, corrosion, or loose connections
-
Measure circuit voltage, resistance, and continuity to identify the fault type
-
Check for technical service bulletins related to this code for your specific vehicle
Sources 2
This page is built from documented references. Verify against your own service info before repair work.
- SAE J2012Diagnostic Trouble Code Definitions (defines the generic OBD-II code ranges)
- Cross-checked against the SAE J2012:2002 DTC table (2026-08-27)archived scan of the SAE standard — readable copy, not SAE’s current edition
P0689 on Diesel, EV & Equipment
The same code ID appears across other engines and platforms. The diagnostic flow varies by manufacturer — these are the platform-specific breakdowns:
Commonly Affected Vehicles
- 2008-2018 Ford F-150
- 2010-2020 Toyota Camry
- 2009-2019 Honda Accord
- 2011-2020 Chevrolet Silverado
Related Codes
Explore More
Was this helpful?
Send this to whoever is fixing the car — your mechanic, or the person asking what the light means.