U0297 — Lost Communication With AC to DC Converter Control Module "B"

vehicle network

Is it safe to drive?

Drive with caution Depends on what is affected. A single dead convenience module is fine to drive with; loss of communication with engine, braking or steering modules is not. If multiple critical systems drop out, do not drive.

How to diagnose with an OBD scanner

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm U0297 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Check for companion codes and TSBs Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many U0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the vehicle network (CAN bus) communication for damage, corrosion, chafing or poor contact.
  4. Subsystem check Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
  5. Subsystem check Scan all modules: the one that does not respond is either the culprit or downstream of the break.
  6. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0297 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U0297 (parts and labor, USD, independent shop rates): Repair CAN wiring or connectors: $100–$400; Remove interfering aftermarket device: $0–$150; Replace the faulty control module: $300–$1,500. Overall, fixing U0297 usually costs between $0 and $1,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Common questions

What does OBD2 code U0297 mean?

Lost Communication With AC to DC Converter Control Module "B" (U0297): a vehicle network fault affecting the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Most often caused by a faulty module pulling the bus down, water ingress in harness junctions, damaged CAN bus wiring or short to power/ground.

How do I diagnose U0297 myself?

Start with a scan: confirm U0297, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the vehicle network (CAN bus) communication, and verify the suspect component against live data before buying parts.

How much does it cost to fix U0297?

Repair CAN wiring or connectors — $100–$400; Remove interfering aftermarket device — $0–$150; Replace the faulty control module — $300–$1,500. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.

What are the symptoms of U0297?

Drivers most often notice: random, hard-to-reproduce electrical glitches, intermittent loss of functions (gauges, windows, steering assist), no-start or intermittent starting in some cases, modules intermittently not communicating with the scanner.

Is it safe to drive with U0297?

Depends on what is affected. A single dead convenience module is fine to drive with; loss of communication with engine, braking or steering modules is not. If multiple critical systems drop out, do not drive.

What does U0297 mean?

Seeing U0297 on your scanner? The control unit has caught the vehicle network (CAN bus) communication operating outside its calibrated window. The formal description is “Lost Communication With AC to DC Converter Control Module "B"”, and the code is grouped under vehicle network faults.

To set U0297, the control module compares live readings of the vehicle network (CAN bus) communication against calibrated limits, usually over several drive cycles. Alongside the code it stores a freeze frame — a snapshot of rpm, load, coolant temperature and vehicle speed at the moment of failure. Reading that snapshot first saves diagnostic time.

What causes U0297?

  • water ingress in harness junctions
  • aftermarket equipment interfering with the bus
  • a faulty module pulling the bus down
  • damaged CAN bus wiring or short to power/ground
  • corroded connectors, especially in wet areas

Common symptoms of U0297

  • random, hard-to-reproduce electrical glitches
  • intermittent loss of functions (gauges, windows, steering assist)
  • no-start or intermittent starting in some cases
  • modules intermittently not communicating with the scanner
  • multiple warning lights on at once

How to diagnose U0297

  1. Connect an OBD2 scanner, confirm U0297 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. Related codes often reveal the real root cause. Also check manufacturer technical service bulletins (TSB) for your make and model — many U0xxx issues have factory fixes or software updates. Search by VIN on the manufacturer site or nhtsa.gov.
  3. Visually inspect the wiring harness and connectors related to the vehicle network (CAN bus) communication for damage, corrosion, chafing or poor contact.
  4. Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
  5. Scan all modules: the one that does not respond is either the culprit or downstream of the break.
  6. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0297 does not return.

How to fix U0297

Start with the cheapest and most common causes before replacing expensive parts:

  • Repair CAN wiring or connectors — $100–$400
  • Remove interfering aftermarket device — $0–$150
  • Replace the faulty control module — $300–$1,500

How much does it cost to fix U0297?

Repair cost depends on which component actually failed. Typical scenarios for U0297 (parts and labor, USD, independent shop rates):

  • Repair CAN wiring or connectors: $100–$400
  • Remove interfering aftermarket device: $0–$150
  • Replace the faulty control module: $300–$1,500

Overall, fixing U0297 usually costs between $0 and $1,500. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.

Can you drive with U0297?

Depends on what is affected. A single dead convenience module is fine to drive with; loss of communication with engine, braking or steering modules is not. If multiple critical systems drop out, do not drive.

Related OBD2 codes