U0106 — Lost Communication With Glow Plug Control Module
OBD2 code U0106 flags a problem with the diesel glow plug system (lost communication with glow plug control module). The car is usually drivable while you plan the repair. Common culprits: blown fuse in the glow plug circuit, burned-out glow plug, damaged glow plug wiring or connector.
vehicle network
Is it safe to drive?
Short-term driving is OK Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.
How to diagnose with an OBD scanner
- Read the code and freeze frame Connect an OBD2 scanner, confirm U0106 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
- Check for companion codes and TSBs 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.
- Inspect wiring and connectors Visually inspect the wiring harness and connectors related to the diesel glow plug system for damage, corrosion, chafing or poor contact.
- Subsystem check Measure resistance of each glow plug — an open plug reads infinite resistance.
- Subsystem check Check voltage at the glow plug rail during the pre-glow phase.
- Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0106 does not return.
Approximate repair cost
Repair cost depends on which component actually failed. Typical scenarios for U0106 (parts and labor, USD, independent shop rates): Replace a full set of glow plugs: $250–$600; Replace the glow plug relay/module: $150–$450; Replace one glow plug: $80–$200. Overall, fixing U0106 usually costs between $80 and $600. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.
Common questions
How do I diagnose U0106 myself?
Start with a scan: confirm U0106, save the freeze frame and note any companion codes. Then inspect the wiring and connectors related to the diesel glow plug system, and verify the suspect component against live data before buying parts.
Will U0106 clear itself?
Sometimes U0106 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 is the most common cause of U0106?
The most common causes are: blown fuse in the glow plug circuit, burned-out glow plug, damaged glow plug wiring or connector.
What are the symptoms of U0106?
Drivers most often notice: Check Engine Light on, rough idle until warmed up, hard starting in cold weather, white smoke after a cold start.
How much does it cost to fix U0106?
Replace a full set of glow plugs — $250–$600; Replace the glow plug relay/module — $150–$450; Replace one glow plug — $80–$200. Exact cost depends on the root cause, your vehicle and local labor rates — a proper diagnosis is the cheapest first step.
What does U0106 mean?
The engine control module sets U0106 when it detects a fault in the diesel glow plug system. In practical terms: lost communication with glow plug control module. The code belongs to the vehicle network group of OBD2 codes.
This code does not appear from a single bad reading: the module must see the fault condition repeat under defined operating conditions before it turns on the warning light. The freeze frame captured with U0106 — engine load, rpm, temperature, speed — tells you exactly when the problem occurs, so reproduce those conditions when testing.
Common symptoms of U0106
- Check Engine Light on
- rough idle until warmed up
- hard starting in cold weather
- white smoke after a cold start
- glow plug warning light staying on
What causes U0106?
- burned-out glow plug
- corroded glow plug connectors
- faulty glow plug relay or control module
- damaged glow plug wiring or connector
How to diagnose U0106
- Connect an OBD2 scanner, confirm U0106 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
- 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.
- Visually inspect the wiring harness and connectors related to the diesel glow plug system for damage, corrosion, chafing or poor contact.
- Measure resistance of each glow plug — an open plug reads infinite resistance.
- Check voltage at the glow plug rail during the pre-glow phase.
- Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0106 does not return.
How to fix U0106
Start with the cheapest and most common causes before replacing expensive parts:
- Replace a full set of glow plugs — $250–$600
- Replace the glow plug relay/module — $150–$450
- Replace one glow plug — $80–$200
How much does it cost to fix U0106?
Repair cost depends on which component actually failed. Typical scenarios for U0106 (parts and labor, USD, independent shop rates):
- Replace a full set of glow plugs: $250–$600
- Replace the glow plug relay/module: $150–$450
- Replace one glow plug: $80–$200
Overall, fixing U0106 usually costs between $80 and $600. An accurate diagnosis before buying parts saves money — the most expensive scenario is rarely the first one to check.
Can you drive with U0106?
Safe to drive once the engine is started and warmed up. The main risk is cold-weather starting: with several dead plugs the engine may not start on a cold morning. Fix before winter.