OBD-II trouble code
U0113: Lost Communication with Emissions Critical Control Information
A module on the network stopped receiving the emissions-critical data it expects from another controller. Usually a wiring, power, or ground fault on the bus, it can disable emissions monitors, trip the check engine light, and cause a failed inspection.
Quick facts
- System
- Network
- Category
- Network Communication
- Severity
- Medium severity
- Drivable
- Usually safe to drive short-term
- Repair cost range
- $120 – $1,200
- DIY difficulty
- Advanced DIY
What does U0113 mean?
U0113 is set when a module on the vehicle's communication network stops receiving the emissions-critical control information it relies on from another controller — typically data passed between the engine control module and an emissions-related module. Modern vehicles share emissions data over the network so that catalyst, EVAP, fuel, and air-system monitors can run correctly. When that stream of emissions-critical messages goes silent, the receiving module records U0113 because it can no longer verify the emissions system is being controlled as designed.
The causes are the usual lost-communication suspects rather than a tailpipe problem in themselves. A module may have lost power or ground through a blown fuse, corroded ground, or failed relay. The communication wiring or a connector between the modules can be damaged, chafed, or corroded. The internal communication circuitry of either module can fail, or another module on the bus can disrupt the network for everyone. Low 12-volt system voltage can cause intermittent dropouts that set the code and then clear.
The practical impact is mostly emissions-related. With the emissions-critical data missing, readiness monitors may not complete, so the vehicle can fail a smog or inspection test even if it otherwise runs fine. The check engine light usually comes on, sometimes alongside companion communication or emissions codes. Driveability is often normal, but the underlying communication fault should be repaired so the emissions monitors can run and the vehicle can pass inspection.
Common causes
- Blown power or ground fuse for one of the involved modules
- Corroded or loose ground affecting an emissions-related module
- Damaged, chafed, or corroded communication wiring between modules
- Backed-out or corroded terminals at a module connector
- Failed internal communication circuitry in the sending or receiving module
- Another module on the bus disrupting network communication
- Low 12-volt system voltage from a weak or failing battery
- Software or configuration mismatch after a module replacement
Symptoms
- Check engine light on
- Emissions readiness monitors won't complete ('not ready')
- Failed smog check or state emissions inspection
- Companion communication or emissions trouble codes stored
- Scan tool shows a module not reporting expected emissions data
- Driveability often normal, with no obvious running problem
- Code may be intermittent and reappear after sitting
Diagnostic steps
- 1.Scan all modules and record every stored code; U0113 often appears with other communication or emissions codes that point to the affected module.
- 2.Check the readiness monitors to confirm which emissions monitors are failing to complete.
- 3.Inspect the power and ground for the involved modules, including fuses and ground points.
- 4.Inspect the communication wiring and connectors between the modules for chafing, corrosion, and loose terminals.
- 5.Measure the communication bus lines and verify continuity between the modules.
- 6.Test the 12-volt battery and charging, since low voltage can cause intermittent communication loss.
- 7.If wiring, power, and ground are good, suspect an internal module fault and confirm software/configuration is correct before replacing a module.
Repair cost
$120 – $1,200
A blown fuse, corroded ground, or connector repair is the cheapest fix at $120-$350 once located. Wiring repair typically runs $200-$600. Diagnostic time often adds $100-$200. If a module must be replaced and programmed, the cost can reach $600-$1,200 or more depending on the module. Repairing the communication fault is also what lets the emissions monitors run so the vehicle can pass inspection.
Estimate your repair
Run the numbers for your vehicle
Open the Repair Cost Estimator with module communication / can bus diagnosis preselected. Adjust labor rate and vehicle category to fit your situation.
DIY vs shop
This is an advanced DIY job. It typically requires specialty tools, scan-tool access, lifting equipment, or careful sequencing to avoid causing new failures. Plan for extended downtime and have a backup vehicle. Most owners are better served by a shop that has done this repair before.