Open, chafed, or corroded wiring in the CAN bus circuit between the ECM and glow plug control module 2; A failed glow plug control module 2, often due to internal water intrusion or heat damage; Poor ground connection at the glow plug control module 2 mounting point or engine block; Blown fuse or missing power feed to the glow plug control module 2, which prevents it from powering up and communicating; Corroded or backed-out pins in the module connector, especially on vehicles exposed to road salt; A shorted or damaged CAN bus segment shared with another module that pulls the network down; A software or configuration issue in the ECM after a battery replacement or module replacement

DTC codes / U01xx · Lost communication with a control module / U019C

U019CLost Communication With Glow Plug Control Module 2

Q: What does code U019C mean?

Lost Communication With Glow Plug Control Module 2. U019C is a communication fault where the engine control module (ECM) has lost the controller area network (CAN) signal from the glow plug control module 2, which is the second glow plug controller on vehicles that use two separate modules. The ECM sets this code when it expects regular status messages from that module and none arrive within the programmed timeout window, so the fault is electrical or network-related rather than a glow plug performance problem.

U019C is a communication fault where the engine control module (ECM) has lost the controller area network (CAN) signal from the glow plug control module 2, which is the second glow plug controller on vehicles that use two separate modules. The ECM sets this code when it expects regular status messages from that module and none arrive within the programmed timeout window, so the fault is electrical or network-related rather than a glow plug performance problem.

SystemNetwork

Code typeGeneric (all makes)

SeverityMedium

Fix difficultyIntermediate

AreaLost communication with a control module

Symptoms you may notice

Illumination of the check engine light or glow plug warning lamp, often with no other symptoms besides the warning light
Hard cold starting or a rough idle immediately after start-up because glow plug heating is not being commanded
Extended cranking time in cold weather and white exhaust smoke until the engine warms up
A stored code in the ECM with no drivability complaint in warm weather, since glow plugs are only needed below a certain temperature
Other communication codes stored in multiple modules if the fault is on a shared CAN bus segment rather than the module itself

Common causes, most likely first

Open, chafed, or corroded wiring in the CAN bus circuit between the ECM and glow plug control module 2
A failed glow plug control module 2, often due to internal water intrusion or heat damage
Poor ground connection at the glow plug control module 2 mounting point or engine block
Blown fuse or missing power feed to the glow plug control module 2, which prevents it from powering up and communicating
Corroded or backed-out pins in the module connector, especially on vehicles exposed to road salt
A shorted or damaged CAN bus segment shared with another module that pulls the network down
A software or configuration issue in the ECM after a battery replacement or module replacement

How to diagnose and fix it

Scan all modules for communication codes and record which modules are online to determine whether the fault is isolated to glow plug control module 2
Inspect the glow plug control module 2 connector for corrosion, water intrusion, and backed-out pins, then clean and reseat it
Check the fuse and power feed at the glow plug control module 2 with a test light or multimeter to confirm the module is receiving battery voltage
Measure CAN bus resistance and voltage at the module connector to verify the network is intact and not shorted to ground or power
Perform a wiggle test on the harness while watching live communication status to catch intermittent wiring faults
Substitute a known-good glow plug control module 2 or reflash the ECM only after wiring and power checks pass
Clear the code and verify communication returns, then road test and confirm the code does not reset

Why glow plug module 2 loses communication

This code is often set by a weak or corroded ground at the module rather than a failed module, so always load-test the ground circuit before condemning the part.
On vehicles with two glow plug control modules, a single failed module can set U019C while the engine still starts normally in mild weather, which leads owners to ignore a fault that will strand them in winter.
A low battery or a recent battery replacement can trigger this code because the module may not boot up correctly if voltage drops during cranking, so check for a stored history code before replacing hardware.
The glow plug control module 2 shares its CAN segment with other modules on many vehicles, so a fault in an unrelated module can pull the bus down and set U019C as a side effect.
After replacing the module, some vehicles require a configuration or adaptation step with a scan tool, and skipping it will leave the code stored even though the new module is good.

Can I keep driving with U019C?

You can usually drive the vehicle in warm weather because the engine will start without glow plug heating, but avoid cold-weather driving and long cranking periods until the fault is repaired. If the engine is hard to start or produces heavy white smoke, stop driving and have the circuit diagnosed to prevent battery drain and starter wear.

Tools that help

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Guidance is general and written for all OBD-II vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.