U0113 Lost Communication with Critical Emission Module
Diagnostic trouble code U0113 indicates a loss of communication with a control module that is critical for the vehicle's emission system. On the vehicle's communication network (typically CAN bus), the powertrain control module (PCM) or the main control module cannot send or receive necessary data with the affected module. This prevents proper execution of emission control strategies. The fault is detected when periodic messages or responses to diagnostic commands from the critical module are missing, causing a network timeout error.
1. Commonly Affected Makes
This is a generic OBD2 code, potentially applicable to any manufacturer using this diagnostic standard.
2. Most Common Causes
- Damaged or internally failed emission-critical control module
- Open circuit or short to ground in the CAN communication bus
- Short circuit to voltage in the communication wiring
- Corroded, bent, or poorly seated electrical connections at the module connector
- Blown fuse or defective relay powering the control module
- Intermittent wiring faults due to vibration or extreme heat
- Electromagnetic interference (EMI) on the communication network
3. Symptoms You Will Notice
- Check Engine Light illuminated
- Vehicle may fail emissions test or run poorly
4. Step-by-Step Diagnosis
Scan for all stored codes and freeze frame data
Inspect the module connector for corrosion, bent pins, or poor contact
Check power and ground at the module (fuse, relay, wiring)
Test CAN bus wiring for opens, shorts, or high resistance
Verify module communication using a scan tool or oscilloscope
If wiring is good, suspect a failed module and replace if necessary
5. Frequently Asked Questions
Is it safe to drive?▼
Driving is not recommended because the emission control system may be compromised, potentially causing further damage or leaving you stranded. Have the vehicle diagnosed promptly.
How much does it cost to fix?▼
Repair costs typically range from $150 to $1,200 depending on the root cause. Simple wiring repairs may cost $150–$400, while module replacement can run $500–$1,200 including labor.