P0E99: DC/DC Converter Voltage Sensor C Circuit

What it means

The ECM detects a circuit fault on the dc/dc converter voltage sensor c circuit. Reading cannot be used reliably for control.

At a glance

• Usually lights the check-engine light
• The engine or gearbox may go into limp mode

How it works

DC/DC converter current sensor B measures current in the converter circuit so the control module can manage converter operation. This code sets when the sensor B circuit is faulty and its reading cannot be relied on, commonly because the sensor, wiring, or connector has failed.

Common causes

Most likely first.

1. Sensor failed
2. Wiring or connector fault

Symptoms

• Hybrid or EV system warning light
• Reduced power or limited electric drive
• Charging may be limited
• Reduced electric range

How to diagnose it

1. Save freeze-frame data and review DC/DC converter current sensor B live data with converter voltage and charging status to see when the signal becomes unreliable.
2. Inspect the current sensor B connector and nearby wiring for loose fit, corrosion, chafing, or physical damage.
3. Check sensor B power, ground, and signal paths using the vehicle's wiring information and manufacturer's test procedure.
4. Compare sensor B output with the manufacturer's specification as converter operation changes.
5. If the wiring and connector pass, test current sensor B and the DC/DC converter to isolate the circuit fault.

Common fixes

• Secure a loose DC/DC converter current sensor B connector.
• Repair damaged wiring or corroded terminals in the sensor B circuit.
• Replace current sensor B if it fails the specified tests.
• Repair the DC/DC converter if its fault is disrupting the current sensor B circuit.

Can I keep driving?

Limit driving if the vehicle reports reduced electric drive or charging, since power and electric range may be reduced. If the warning escalates or the vehicle limits power, stop safely and arrange assistance.