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U0237 — Lost Communication Digital Audio Control Module C

Generic OBD-II · all makesNetwork / communication

This code indicates the Powertrain Control Module (PCM) or network gateway has lost Controller Area Network (CAN) communication with Digital Audio Control Module C, a unit that typically manages audio amplification or processing for a specific vehicle zone. The module is not responding to expected messages within the manufacturer-specified timeframe.

Symptoms

What causes it — most likely first

1. Digital Audio Control Module C internal failure

The module may have suffered an internal circuit failure, memory corruption, or lost its power/ground supply due to internal fuse or circuit damage.

2. Open or short in CAN bus wiring

Breaks, shorts to power/ground, or high resistance in the twisted-pair CAN high and CAN low wires running to the module interrupt data transmission.

3. Corroded or loose connectors

Moisture intrusion, terminal spread, or oxidation at the module's harness connector creates intermittent or permanent open circuits in communication or power lines.

4. Wiring harness physical damage

Chafing at mounting brackets, pinch points from previous repairs, or rodent damage can sever communication lines without blowing fuses.

5. PCM or network gateway malfunction

Rare. Consider only if multiple unrelated modules simultaneously report lost communication and the CAN bus integrity is verified good.

How it's diagnosed

  1. Visually inspect the module connectors and wiring harness for corrosion, terminal damage, or looseness; wiggle-test harnesses while monitoring live data
  2. Verify battery voltage, ground continuity, and ignition-switched power at the module electrical connector with a digital multimeter
  3. Measure CAN bus voltage (should read approximately 2.5V on each line) and resistance (approximately 60 ohms across high/low if properly terminated) at the module connector
  4. Perform manufacturer-specific module self-tests or reset procedures using a scan tool capable of bi-directional communication
  5. Evaluate the PCM or gateway module only if numerous unrelated communication codes are present and all wiring tests pass

Code facts & related codes

SystemNetwork / communication
StandardizationSAE generic — identical on every make
Related codesU0230 — Lost Communication Rear Gate ModuleU0231 — Lost Communication Rain Sensing ModuleU0232 — Lost Communication Side Obstacle DetecU0233 — Lost Communication Side Obstacle DetecU0234 — Lost Communication Convenience Recall U0235 — Lost Communication Front Distance Rang

Frequently asked

Is it safe to drive with this code active?

Yes. This fault affects only the audio system and does not compromise engine operation, braking, or steering safety. However, you may have no audio output from the affected zone.

My technician says I need a new PCM. Is that correct?

Almost certainly not. For a single-module communication fault like U0237, the PCM is rarely the root cause. The problem is almost always the audio module itself, its wiring, or connectors. PCM replacement should only be considered if the vehicle has multiple unrelated communication codes and the bus network is proven fault-free.

What does 'Module C' mean?

It designates this as the third digital audio control unit in the vehicle's network architecture, often corresponding to a specific amplifier or processor for rear-seat audio, subwoofers, or a distinct audio channel separate from Modules A and B.

Could this cause my battery to die?

Possibly. If the module has failed in a state that keeps the CAN bus awake continuously, it may cause parasitic battery drain. If you experience overnight battery discharge, have the system diagnosed promptly.