U011A — Lost Communication With Exhaust Gas Sensor Module

U011A — Lost Communication With Exhaust Gas Sensor Module. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: aftermarket equipment interfering with the bus, poor grounds or low battery voltage, corroded connectors, especially in wet areas.

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 U011A 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 U011A does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U011A (parts and labor, USD, independent shop rates): Replace the faulty control module: $300–$1,500; Remove interfering aftermarket device: $0–$150; Repair CAN wiring or connectors: $100–$400. Overall, fixing U011A 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 is the most common cause of U011A?

The most common causes are: aftermarket equipment interfering with the bus, poor grounds or low battery voltage, corroded connectors, especially in wet areas.

Is it safe to drive with U011A?

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 are the symptoms of U011A?

Drivers most often notice: intermittent loss of functions (gauges, windows, steering assist), multiple warning lights on at once, random, hard-to-reproduce electrical glitches, no-start or intermittent starting in some cases.

How do I diagnose U011A myself?

Start with a scan: confirm U011A, 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 U011A?

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

What does U011A mean?

Seeing U011A 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 Exhaust Gas Sensor Module”, and the code is grouped under vehicle network faults.

This code does not appear from a single bad reading: the module must see the fault condition repeat under defined operating conditions before it turns on the warning light. The freeze frame captured with U011A — engine load, rpm, temperature, speed — tells you exactly when the problem occurs, so reproduce those conditions when testing.

What causes U011A?

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

Common symptoms of U011A

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

How to diagnose U011A

  1. Connect an OBD2 scanner, confirm U011A 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 U011A does not return.

How to fix U011A

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

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

How much does it cost to fix U011A?

Repair cost depends on which component actually failed. Typical scenarios for U011A (parts and labor, USD, independent shop rates):

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

Overall, fixing U011A 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 U011A?

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