U0407 — Invalid Data Received From Glow Plug Control Module

OBD2 code U0407 flags a problem with the diesel glow plug system (invalid data received from glow plug control module). The car is usually drivable while you plan the repair. Common culprits: faulty glow plug relay or control module, burned-out glow plug, blown fuse in the glow plug circuit.

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

  1. Read the code and freeze frame Connect an OBD2 scanner, confirm U0407 is stored, and save the freeze frame data — it shows engine conditions when the fault was detected.
  2. 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.
  3. 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.
  4. Subsystem check Measure resistance of each glow plug — an open plug reads infinite resistance.
  5. Subsystem check Check voltage at the glow plug rail during the pre-glow phase.
  6. Verify the repair Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0407 does not return.

Approximate repair cost

Repair cost depends on which component actually failed. Typical scenarios for U0407 (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 U0407 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

What are the symptoms of U0407?

Drivers most often notice: white smoke after a cold start, rough idle until warmed up, hard starting in cold weather, Check Engine Light on.

How much does it cost to fix U0407?

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.

Is it safe to drive with U0407?

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 do I diagnose U0407 myself?

Start with a scan: confirm U0407, 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 U0407 clear itself?

Sometimes U0407 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 U0407 mean?

The engine control module sets U0407 when it detects a fault in the diesel glow plug system. In practical terms: invalid data received from glow plug control module. The code belongs to the vehicle network group of OBD2 codes.

To set U0407, the control module compares live readings of the diesel glow plug system against calibrated limits, usually over several drive cycles. Alongside the code it stores a freeze frame — a snapshot of rpm, load, coolant temperature and vehicle speed at the moment of failure. Reading that snapshot first saves diagnostic time.

Common symptoms of U0407

  • white smoke after a cold start
  • rough idle until warmed up
  • hard starting in cold weather
  • Check Engine Light on
  • glow plug warning light staying on

What causes U0407?

  • faulty glow plug relay or control module
  • damaged glow plug wiring or connector
  • corroded glow plug connectors
  • blown fuse in the glow plug circuit

How to diagnose U0407

  1. Connect an OBD2 scanner, confirm U0407 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 diesel glow plug system for damage, corrosion, chafing or poor contact.
  4. Measure resistance of each glow plug — an open plug reads infinite resistance.
  5. Check voltage at the glow plug rail during the pre-glow phase.
  6. Clear the code, complete a full drive cycle including the conditions from the freeze frame, and confirm U0407 does not return.

How to fix U0407

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 U0407?

Repair cost depends on which component actually failed. Typical scenarios for U0407 (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 U0407 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 U0407?

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.

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