Sensor Reference Voltage Circuit Low
The P0698 code indicates that the Engine Control Module (ECM) has detected a low voltage condition on the 5-volt reference circuit that powers various sensors (e.g., throttle position, crankshaft position, manifold absolute pressure). This can be caused by a short to ground, a faulty sensor, or a damaged wiring harness. The ECM monitors this voltage and sets the code when it falls below a calibrated threshold, often affecting multiple sensor readings and engine performance.
01. Most Common Causes
- Short to ground in the 5-volt reference circuit
- Faulty sensor (e.g., throttle position sensor, MAP sensor)
- Damaged wiring or connectors
- Corroded or loose electrical connections
- Failed ECM (rare)
02. Symptoms You Will Notice
- Check Engine Light illuminated
- Engine stalling or rough idle
- Poor acceleration or hesitation
- Reduced fuel economy
- Multiple sensor-related codes may appear
03. Step-by-Step Diagnosis
Step 1: Use a scan tool to confirm P0698 and check for additional codes.
Step 2: Visually inspect the 5-volt reference circuit wiring and connectors for damage, corrosion, or shorts.
Step 3: Disconnect sensors one by one while monitoring the reference voltage with a multimeter to isolate the short.
Step 4: If voltage returns to normal after disconnecting a sensor, replace that sensor.
Step 5: If no sensor is at fault, repair or replace the wiring harness section with the short.
04. Commonly Affected Makes
05. Frequently Asked Questions
Is it safe to drive with this code?▼
It is not recommended to drive with P0698 as it can cause erratic sensor readings, leading to poor engine performance, stalling, or even damage to the catalytic converter. Have the vehicle diagnosed and repaired promptly.
How much does it cost to fix?▼
The cost typically ranges from $50 to $150 for diagnosis and repair, depending on the cause. Replacing a faulty sensor may cost $50-$100, while wiring repairs can be $100-$200. ECM replacement is rare and more expensive.