U0073 on 2007-2011 Toyota Camry: Control Module Communication Bus 'A' Off Causes and Fixes

What's Unique About the 2007-2011 Toyota Camry

For the XV40 generation Camry, the U0073 code is overwhelmingly linked to an internal failure of the ABS control module. While wiring or battery issues can be the cause on any car, numerous documented cases on this specific Camry point to the ABS module itself failing—often due to cracked internal solder joints from heat and vibration—and taking down the entire communication network. This failure causes a cascade of seemingly unrelated warning lights (ABS, Brake, VSC, Check Engine) and symptoms like fluctuating gauges, making diagnosis confusing without focusing on the ABS module as the primary suspect.

Symptoms You May Notice

• Multiple warning lights illuminated simultaneously (Check Engine, ABS, VSC, Brake, Traction Control).
• Instrument cluster gauges (speedometer, tachometer, temperature) fluctuating wildly or dropping to zero.
• Loss of power steering assist.
• Engine hesitation, stalling, or a no-start condition.
• Transmission may shift erratically or seem stuck in one gear.
• Inability for an OBD-II scanner to communicate with some or all modules.
• A/C may blow hot air due to loss of communication with related modules.
🎬 Watch this fix for intermittent cluster and AC power loss.

Most Likely Causes

1. Faulty ABS Control Module 🔴 High Probability There are widespread, documented cases for this Camry generation where the ABS module fails internally, shorting out the CAN bus network and causing a U0073 code. This is the most common point of failure for these specific symptoms. NHTSA ODI #10597902 notes a case where a service writer found the ABS actuator was shorting out intermittently, triggering "U0073 Control Module Bus Off."
   How to confirm: A technician can use an oscilloscope to see the corrupted CAN signal at the OBD-II port. A definitive DIY diagnostic step is to disconnect the large electrical connector from the ABS module. If communication is restored between other modules (e.g., the scanner can now talk to the ECM) and the gauges return to normal (though ABS/Brake lights will remain on), the ABS module is faulty.
   Typical fix: Replace the ABS module/actuator assembly or send the original electronic module to a specialist for repair, which is often cheaper and avoids the need for reprogramming. After replacement, a zero-point calibration may be required. 🎬 Watch: Step-by-step guide to replacing the ABS control module.
   Est. part cost: $400-$1200 for a new or remanufactured unit, or $150-$250 for a mail-in repair service.
2. Damaged CAN Bus Wiring or Connectors 🟡 Medium Probability Wiring can be damaged by rodents, previous repairs, or corrosion in areas exposed to moisture, like near the firewall or under the carpet.
   How to confirm: Visually inspect the main wiring harnesses, especially around the engine bay, under the dashboard, and near the ABS module. Look for chafed wires, corrosion in connectors, or signs of rodent damage. A multimeter can be used to check for continuity and shorts between the CAN High (Pin 6) and CAN Low (Pin 14) wires. Resistance between the two should be ~60 ohms with the battery disconnected.
   Typical fix: Repair the damaged section of the wiring harness or clean/replace the corroded connector.
   Est. part cost: $10-$100
3. Weak Battery or Failing Alternator ⚪ Low Probability
   How to confirm: Test the battery voltage with the engine off (should be ~12.4-12.6V). Test the alternator output with the engine running (should be ~13.5-14.5V). Low system voltage can cause modules to malfunction and drop off the network, sometimes triggering a U0073 code. One owner on Reddit fixed persistent ABS/VSC errors and a U0073 code simply by replacing a bad battery that was reading low voltage.
   Typical fix: Replace the battery and/or alternator.
   Est. part cost: $150-$500

Rare But Worth Checking

• Faulty Engine Control Module (ECM): While less common than the ABS module, the ECM is a key player on the CAN bus. If it fails, it can disrupt the entire network. This is usually diagnosed after all other possibilities are eliminated.
• Faulty Gateway Module: On some vehicles, a dedicated gateway module manages CAN bus traffic. On the 2007-2011 Camry, the ABS module often serves this function, but if a separate gateway exists and fails, it can cause a U0073. Diagnosis involves checking if any communication is possible through the OBD-II port.
• Aftermarket Electronics: Improperly installed remote starters, alarms, or audio equipment can interfere with or damage the CAN bus wiring, leading to communication failures.

Diagnosis Steps

1. Check and charge the battery. Ensure system voltage is stable and above 12.4V with the engine off.
2. Perform a full system scan with a high-quality scanner to see which modules are reporting 'no communication'. Note if the scanner itself cannot connect.
3. Visually inspect the main wiring harness for obvious signs of damage, corrosion, or loose connections, paying close attention to the area around the ABS module and ECM.
4. With the ignition off and battery disconnected, measure the resistance between Pin 6 (CAN-H) and Pin 14 (CAN-L) on the OBD-II port. A healthy network should read approximately 60 Ω. A reading of 120 Ω suggests a break in the circuit or a missing terminating resistor, while a reading near 0 Ω indicates a short circuit.
5. If the signal is corrupted or resistance is wrong, begin unplugging modules one by one from the CAN bus, starting with the ABS module as it is the most likely culprit.
6. After unplugging the ABS module, re-connect the battery and turn the ignition on. Check if communication is restored with other modules (e.g., can the scanner now read the ECM?) and if the gauges behave normally. If so, the ABS module is confirmed as the faulty part.
7. If the problem persists, a detailed wire-by-wire diagnosis of the CAN harness for shorts or opens is required, which is best left to a professional.

Parts You'll Likely Need

• ABS Actuator and Pump Assembly (OEM #Commonly 44050-06070, 44050-33240. Bosch part numbers include 0265800534. Always verify with VIN.) — This is the most frequently documented failure point on this Camry generation that causes a U0073 code by bringing down the entire CAN network.
  Trusted brands: Toyota (OEM), Bosch (OEM supplier), Cardone (remanufactured), Mail-in repair services on eBay
  OEM price range: $950-$1210.
  Aftermarket price range: $400-$900 for remanufactured units, or ~$170 for a mail-in repair service.
• Automotive Battery — Low system voltage is a simple but common cause of complex electronic communication faults. It should be the first thing checked.
  Trusted brands: Interstate, DieHard, Duralast
  OEM price range: $200-$300
  Aftermarket price range: $150-$250

Related Codes That Often Appear With This One

• U0100 — Lost Communication with ECM/PCM. This code is often logged by other modules when the U0073 fault occurs, as they can no longer hear from the engine computer.
• U0129 — Lost Communication With Brake System Control Module. This is logged by other modules when the ABS module is the source of the network failure.
• C1241 — Low or High Battery Voltage. This code is often stored in the ABS module alongside U0073, either as a cause (bad battery) or a symptom of the module's internal electronic failure.
• P1604 — Startability Malfunction. This Toyota-specific code can be set when the ECM loses communication with other essential modules required for starting.

Platform-Specific Known Issues

• 2009 Camry No Communication and Erratic Gauges: A detailed diagnostic video on YouTube for a 2009 Camry showed th

Mechanic-Grade Diagnostic Values

• CAN Bus Resistance at ABS Module Connector — expected: 54 to 69 Ω. Failure: A reading outside this range indicates an open, short, or issue in the CAN branch wiring to the ABS module.
• CAN Bus Voltage (Key On, Engine Off) — expected: CAN High (CANH): ~2.5-3.5V, CAN Low (CANL): ~1.5-2.5V. Failure: A flatline voltage, or a line stuck near 0V or 5V, indicates a dead bus or short circuit.
• Skid Control ECU Power Supply (IG1) — expected: 10 to 14 V. Failure: Voltage below 10V can cause the module to malfunction and trigger communication faults like U0073 and C1241.
• Skid Control ECU Ground Resistance — expected: Below 1 Ω. Failure: Resistance above 1 Ω indicates a poor ground connection, which can cause erratic module behavior.

Scan Tool Commands That Help

• Toyota Techstream: CAN Bus Check — To verify which ECUs are present and communicating on the CAN bus. It can help identify which module is not responding, pointing to the source of the U0073 code.
• Toyota Techstream: Health Check — To perform a comprehensive scan of all vehicle modules and retrieve a full list of current, pending, and history codes. This helps build a complete picture of the network failure.
• Toyota Techstream: Active Test (for ABS) — After replacing the ABS module, this function can be used to cycle the ABS pump motor and solenoids to ensure proper function and aid in brake bleeding.

Wiring & Ground Locations

• A19 Connector (Skid Control ECU) — The main electrical connector on the ABS module assembly, located in the engine bay near the battery.. This is the primary connection point for the ABS module. Testing for power, ground, and CAN signals at this connector is a key diagnostic step. Pins 11 (CANH) and 25 (CANL) are the communication lines. Pins 32 and 1 are grounds, and Pin 46 is the ignition power (IG1).
• CAN Junction Connector — Located behind the driver's side kick panel or junction block area. It serves as a hub where multiple CAN bus lines converge.. A fault at this central connector can take down the entire network. Technicians may disconnect branches here to isolate a faulty module or wiring section.
• Engine/Chassis Grounds — Key ground points are located on the valve cover and from the valve cover to the frame near the strut tower.. A poor ground connection for the ECM or other modules can introduce noise or voltage drops that disrupt CAN communication, potentially leading to a U0073 code.

Real Owner Repair Stories

• YouTube channel 'Pine Hollow Auto Diagnostics' (2009 Toyota Camry) — Scanner would not communicate with the vehicle, multiple warning lights, erratic gauges. Codes U0073, C0210, C1241, C1332 were present when communication was briefly possible.
  ❌ Tried (didn't work) Initial scan attempts failed to connect.
  ✅ What actually fixed it The technician observed the CAN signal on an oscilloscope and found it was being corrupted. Tapping on the ABS module caused the signal to drop out completely. Disconnecting the ABS module restored stable communication between the scanner and the other modules. Replacing the ABS module resolved all issues.
• YouTube channel 'William Kincaid' (2007 Toyota Camry) — Speedometer at zero, RPM gauge bouncing, ABS light on, A/C not working.
  ❌ Tried (didn't work) Driving with the faulty module unplugged (this was a temporary measure, not a fix).
  ✅ What actually fixed it The owner removed the electronic portion of the ABS module (the 'Skid Control ECU'), mailed it to a repair service found on eBay for ~$170, and reinstalled the repaired original unit. This fixed all symptoms without needing reprogramming.
• NHTSA ODI #10851309 — An owner reported that the ABS and Brake lights came on, while the speedometer, odometer, and A/C stopped working. The dealer found code U0073 and replaced the ABS actuator assembly, which includes the ABS pump and ECU.
• NHTSA ODI #10704941 — A driver experienced the illumination of various warning lights and noted that the "RPMS started bouncing" due to communication code U0073.
• NHTSA ODI #10614820 — An owner expressed frustration after a dealer confirmed code U0073 pointed to the ABS module, requiring expensive testing to verify the failure.

OEM Part Supersession History

• 44050-06070 → N/A, but has specific application notes.
  Heads up: Part number 44050-06070 is specifically for U.S.-built 2007-2009 Camry models WITHOUT Vehicle Stability Control (VSC). It will not fit Hybrid models, Japanese-built models, or models equipped with VSC. VIN verification is critical when ordering.

Model Year Variations Within This Range

• 2007-Feb 2009: The ABS module part number 44050-06070 is specified for models built up to February 2009. Later 2009-2011 models may use a different part number, especially those with different options like VSC or if they are Japan-built vs. U.S.-built. Always confirm the part number with the vehicle's VIN.

Diagnostic Flowchart

Real Owner Stories

Aggregated from forums and TSBs cited above. Mileages and costs reflect what owners reported in those sources.

Related OBD-II Codes

• C1241 — Too low or too high battery voltage. This code frequently appears alongside U0073 because low system voltage (a weak battery or failing alternator) is a known root cause for modules dropping off the CAN bus network.
• C1332 — Open circuit in right rear wheel speed sensor circuit. This code was documented alongside U0073 in a 2009 Camry where the ABS module had failed internally and shorted the network.
• C0210 — Right rear wheel speed sensor signal fault. Another ABS-related companion code that can trigger when the ABS control module fails and disrupts CAN bus communication.
• U0122 — Lost Communication With Vehicle Dynamics Control Module. Directly related to the primary failure point on this Camry generation, where the ABS/VSC module fails and stops communicating with the network.
• U0100 — Lost Communication With ECM/PCM. Often triggered concurrently with U0073 when a shorted ABS module brings down the entire CAN bus, preventing the scanner and other modules from talking to the engine computer.

Frequently Asked Questions