Code
U0298
Generic
U — Network/User
Lost Communication With DC/DC Converter Control Module A
Views:
UK: 15
EN: 60
RU: 20
AI status
Completed
Completed
100%
Causes
- Faulty or dead DC/DC converter control module
- Open, shorted or corroded wiring/connectors between module and network
- No power or poor ground to the converter module (fuse, relay, battery)
- CAN/LIN bus faults (short to battery/ground, missing termination)
- Module software fault or module in sleep/disabled state
- Intermittent connections due to moisture or vibration
Symptoms
- DTC U0298 stored and communications warning on scan tool
- 12V bus undervoltage or accessories losing power (depending on vehicle)
- Reduced vehicle functionality or limp-home modes in electrified vehicles
- Accessory failures, no charge to auxiliary battery, or warning lights
- Other modules reporting network errors or additional U-codes
What to check
- Retrieve and record all network and module DTCs with a capable scan tool
- Verify vehicle battery state-of-charge and terminal condition
- Check fuses/relays that supply the DC/DC converter module for continuity and correct operation
- Visually inspect the DC/DC converter module connector and wiring for corrosion, bent pins, damage, or loose terminals
- Measure supply voltage and ground at the module connector with key on/off as required
- Measure CAN_H and CAN_L voltages at the module connector and at a good known point on the same bus
Signal parameters
- Vehicle battery voltage at module: nominal ~12–14.5 V (engine running may be higher)
- Module ground resistance: should be low (typically
- CAN idle voltages: CAN_H and CAN_L ~2.5 V (both lines near midpoint) with bus recessive
- CAN dominant state: CAN_H ~3.5 V and CAN_L ~1.5 V during active frames
- Bus termination resistance: ≈60 ohms measured across CAN_H and CAN_L
Diagnostic algorithm
- Connect a diagnostic scan tool and confirm U0298 plus any other related U- or B-/C- codes. Record freeze-frame and module list.
- Verify battery condition and fully charge if low. Inspect battery terminals for corrosion/tightness.
- Check fuses and relays feeding the DC/DC converter module; replace or test as required.
- Perform a visual inspection of the module connector, harness, and nearby components. Repair damaged wiring or terminals.
- Backprobe module power and ground pins. Confirm proper voltages with ignition on and engine running per vehicle spec.
- Measure CAN_H and CAN_L at the module connector and at a known-good node while monitoring the bus with the scan tool or a CAN analyzer. Look for correct idle voltages and active traffic.
Likely causes
- Blown fuse or bad relay supplying the DC/DC converter control module
- Corroded or bent pins at the module connector or gateway harness
- CAN_H or CAN_L shorted to ground/12V, or open circuit
- Low battery voltage preventing module wake-up
- Internal module failure requiring replacement or reflash
Fault status
Status
Lost communication with DC/DC converter control module A — module is not responding on the vehicle data bus.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
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Code
U0298
HYUNDAI
U — Network/User
Lost Communication With DC to DC Converter Control Module “A” | Lost Communication with DC to DC Converter Control Module
Views:
UK: 17
EN: 53
RU: 23
AI status
Completed
Completed
100%
Causes
- Faulty or dead DC/DC converter control module
- Open, shorted or corroded wiring/connectors between module and network
- No power or poor ground to the converter module (fuse, relay, battery)
- CAN/LIN bus faults (short to battery/ground, missing termination)
- Module software fault or module in sleep/disabled state
- Intermittent connections due to moisture or vibration
Symptoms
- DTC U0298 stored and communications warning on scan tool
- 12V bus undervoltage or accessories losing power (depending on vehicle)
- Reduced vehicle functionality or limp-home modes in electrified vehicles
- Accessory failures, no charge to auxiliary battery, or warning lights
- Other modules reporting network errors or additional U-codes
What to check
- Retrieve and record all network and module DTCs with a capable scan tool
- Verify vehicle battery state-of-charge and terminal condition
- Check fuses/relays that supply the DC/DC converter module for continuity and correct operation
- Visually inspect the DC/DC converter module connector and wiring for corrosion, bent pins, damage, or loose terminals
- Measure supply voltage and ground at the module connector with key on/off as required
- Measure CAN_H and CAN_L voltages at the module connector and at a good known point on the same bus
Signal parameters
- Vehicle battery voltage at module: nominal ~12–14.5 V (engine running may be higher)
- Module ground resistance: should be low (typically
- CAN idle voltages: CAN_H and CAN_L ~2.5 V (both lines near midpoint) with bus recessive
- CAN dominant state: CAN_H ~3.5 V and CAN_L ~1.5 V during active frames
- Bus termination resistance: ≈60 ohms measured across CAN_H and CAN_L
Diagnostic algorithm
- Connect a diagnostic scan tool and confirm U0298 plus any other related U- or B-/C- codes. Record freeze-frame and module list.
- Verify battery condition and fully charge if low. Inspect battery terminals for corrosion/tightness.
- Check fuses and relays feeding the DC/DC converter module; replace or test as required.
- Perform a visual inspection of the module connector, harness, and nearby components. Repair damaged wiring or terminals.
- Backprobe module power and ground pins. Confirm proper voltages with ignition on and engine running per vehicle spec.
- Measure CAN_H and CAN_L at the module connector and at a known-good node while monitoring the bus with the scan tool or a CAN analyzer. Look for correct idle voltages and active traffic.
Likely causes
- Blown fuse or bad relay supplying the DC/DC converter control module
- Corroded or bent pins at the module connector or gateway harness
- CAN_H or CAN_L shorted to ground/12V, or open circuit
- Low battery voltage preventing module wake-up
- Internal module failure requiring replacement or reflash
Fault status
Status
Lost communication with DC/DC converter control module A — module is not responding on the vehicle data bus.
Repair difficulty: Medium
Diagnostic time: 1.5 - 3.0 hours
Similar codes
Your experience will help others
+100 karma for a short comment :)
Was this AI description helpful?
Your feedback helps improve AI descriptions.
👍 Like
0
👎 Dislike
0
Send to email