Reference Voltage C Circuit Low
The P0698 code means the vehicle's onboard diagnostic system has detected: Reference Voltage C Circuit Low. This is a critical severity code.
- Keep driving?
- No — stop driving
- DIY difficulty
- hard
- Estimated cost
- $100 - $800 (parts and labor)
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Common Symptoms
- Check Engine Light on
- C-reference sensors reading low
- Vehicle may enter limp mode
- Possible no-start condition
Probable Causes (Ranked by Likelihood)
- Short to ground in 5V reference C 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 is a reference voltage circuit?
The ECM provides a 5-volt reference voltage to power many sensors (TPS, MAP, oil pressure, etc.). If this reference circuit fails, all sensors sharing that reference circuit will read incorrectly, causing multiple codes and drivability issues.
Can one bad sensor take down the reference voltage?
Yes. If a sensor on the reference circuit has an internal short, it can pull down the 5V reference for all sensors sharing that circuit. Disconnect sensors one at a time to find which one is dragging the voltage down.
Will P0698 cause multiple codes?
Yes. When a reference voltage circuit fails, every sensor powered by that circuit loses its reference. This triggers multiple sensor codes simultaneously, which is a strong clue that the underlying issue is the reference circuit itself.
Mechanics Guide Step-by-step diagnosis
Step-by-Step Diagnostic Procedure
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Use a scan tool to read data related to Reference Voltage C
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Inspect all related wiring, connectors, and grounds for damage, corrosion, or loose connections
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Measure circuit voltage, resistance, and continuity to identify the fault type
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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
Commonly Affected Vehicles
- 2008-2018 Ford F-150
- 2010-2020 Chevrolet Silverado
- 2009-2019 Toyota Camry
- 2011-2020 Honda Accord
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