U3023 — Control Module Input Power C Circuit Open

What does OBD2 code U3023 mean?

U3023 — U3023 - Control Module Input Power C Circuit Open. A fault in the vehicle network (CAN bus) communication. Short, gentle driving to a shop is usually possible. Typical causes: poor grounds or low battery voltage, corroded connectors, especially in wet areas, water ingress in harness junctions.

What are the symptoms of U3023?

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

Is it safe to drive with U3023?

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 much does it cost to fix U3023?

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

Will U3023 clear itself?

Sometimes U3023 clears after a few drive cycles if the fault was intermittent — for example a loose connector or a tank of bad fuel. The underlying cause usually remains, so the code tends to return. Clear it once; if it comes back, diagnose rather than erase it repeatedly.

What does U3023 mean?

The engine control module sets U3023 when it detects a fault in the vehicle network (CAN bus) communication. In practical terms: U3023 - control module input power c circuit open. The code belongs to the vehicle group of OBD2 codes.

“Circuit open” means the electrical path of the U3023 - control module input power c circuit is broken: no current flows where the module expects it. This is usually a broken wire, a disconnected or corroded connector, a blown fuse, or an internally open component.

The module monitors this system continuously while driving. When readings fall outside the expected range for a defined number of drive cycles, it stores U3023 and switches on the warning light. Freeze frame data saved with the code shows the exact conditions — rpm, load, temperature, speed — at the moment the fault was detected, which is the best starting point for diagnosis.

What causes U3023?

• broken wire in the U3023 - control module input power c harness
• connector unplugged, backed-out pin or heavy corrosion
• internally open U3023 - control module input power c
• blown fuse feeding the circuit
• a faulty module pulling the bus down
• damaged CAN bus wiring or short to power/ground
• poor grounds or low battery voltage
• water ingress in harness junctions
• corroded connectors, especially in wet areas

Common symptoms of U3023

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

How to diagnose U3023

1. Connect an OBD2 scanner, confirm U3023 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. Do a continuity test end-to-end on the U3023 - control module input power c circuit and wiggle the harness while measuring — intermittent opens show up as fluctuating readings.
5. Measure resistance between CAN-High and CAN-Low at the OBD port with power off — about 60 Ω is healthy.
6. Scan all modules: the one that does not respond is either the culprit or downstream of the break.
7. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U3023 does not return.

How to fix U3023

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

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

How much does it cost to fix U3023?

Repair cost depends on which component actually failed. Typical scenarios for U3023 (parts and labor, USD, independent shop rates):

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

Overall, fixing U3023 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 U3023?

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

• U3000: Control Module
• U3001: Control Module Improper Shutdown
• U3002: Vehicle Identification Number
• U3003: Battery Voltage
• U3004: Accessory Power Relay
• U3005: Retained Accessory Power