Code
P0381
Generic
P — Powertrain
Glow Plug/Heater Indicator Control Circuit/Open
Views:
UK: 25
EN: 66
RU: 32
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring in the indicator control circuit
- Blown fuse or faulty relay for glow plug/heater indicator
- Faulty indicator lamp (burned out bulb or LED) or lamp connector
- Corroded or poor ground
- Damaged connector or pin (terminal loss of continuity)
- Faulty ECM/PCM driver output (rare)
Symptoms
- Glow-plug/preheat indicator (dash lamp) does not illuminate at key-on preheat
- Longer cranking time or harder cold starts (if driver does not activate glow sequence normally)
- Possible illumination of MIL or stored fault in engine control module
- No visual preheat countdown or incorrect preheat behavior displayed
What to check
- Use a scan tool to confirm P0381 is current and review freeze-frame data
- Visually inspect wiring, connectors, and ground points for damage or corrosion
- Check related fuses and relays for the glow/heater and instrument cluster
- Verify the dash indicator lamp works by applying battery voltage at the lamp connector
- Measure voltage at the lamp connector during a glow request (key ON preheat) and check for continuity to the ECM
- Perform a wiggle test on harness and connectors while monitoring lamp operation and any code responses
Signal parameters
- With ignition ON and preheat requested: dash indicator circuit should show a change (battery voltage present or driven to ground depending on design)
- Indicator lamp current: typically small (lamp/LED circuit should draw measurable current; if zero, circuit may be open)
- Continuity: resistance between indicator lamp and ECM harness should be low (near 0 ohms across short connector runs); open = infinite/very high
- Fuse/relay presence: fuse should show battery voltage on both sides; relay contacts should close when energized
- No command: ECM output may be high-impedance; when commanded, ECM output will switch (observe voltage change with respect to ground)
Diagnostic algorithm
- Verify the code with a scan tool, note freeze-frame and related codes (e.g., other glow-plug or power-relay faults).
- Perform a visual inspection of the dash lamp, lamp socket, wiring harness, fuses and relays associated with the glow/heater indicator and preheat system.
- Check the indicator lamp operation by applying battery voltage directly to the lamp socket (confirm the lamp itself is not open).
- Inspect and test fuses and relays: replace any blown fuses and swap or bench-test relays if required.
- With a DVOM, back-probe the indicator circuit at the lamp connector and at the ECM connector. Command the preheat via scan tool (or turn key to preheat) and observe for expected switching (voltage appearing or dropping to ground).
- If no voltage change, check continuity between the lamp and ECM. Repair any open wires, corroded connectors, or poor grounds found.
- If continuity is good and the lamp is functional, test the ECM output driver for switching. If the ECM does not command the output but other systems are normal, suspect ECM output failure and consult manufacturer procedures before replacement.
- After repairs, clear codes and verify proper operation through multiple key cycles and a cold-start check. Re-scan to confirm the code does not return.
Likely causes
- Loose or disconnected connector at indicator lamp or ECM
- Open fuse or stuck/failed relay in the glow/heater circuit
- Broken wire harness (chafing, corrosion, terminal pulled out)
- Bad indicator lamp (bulb or LED cluster) or internal lamp circuit open
- Failed ECM output transistor for the lamp
Fault status
Status
P0381 — Glow Plug/Heater Indicator Control Circuit/Open. ECM detected an open circuit in the glow plug/heater indicator control wiring or components (lamp, fuse, relay, connector, or ECM driver).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
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Code
P0381
GWM
P — Powertrain
- Malfunction in circuit A of the glow plug indicator
Views:
UK: 16
EN: 51
RU: 26
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring in the indicator control circuit
- Blown fuse or faulty relay for glow plug/heater indicator
- Faulty indicator lamp (burned out bulb or LED) or lamp connector
- Corroded or poor ground
- Damaged connector or pin (terminal loss of continuity)
- Faulty ECM/PCM driver output (rare)
Symptoms
- Glow-plug/preheat indicator (dash lamp) does not illuminate at key-on preheat
- Longer cranking time or harder cold starts (if driver does not activate glow sequence normally)
- Possible illumination of MIL or stored fault in engine control module
- No visual preheat countdown or incorrect preheat behavior displayed
What to check
- Use a scan tool to confirm P0381 is current and review freeze-frame data
- Visually inspect wiring, connectors, and ground points for damage or corrosion
- Check related fuses and relays for the glow/heater and instrument cluster
- Verify the dash indicator lamp works by applying battery voltage at the lamp connector
- Measure voltage at the lamp connector during a glow request (key ON preheat) and check for continuity to the ECM
- Perform a wiggle test on harness and connectors while monitoring lamp operation and any code responses
Signal parameters
- With ignition ON and preheat requested: dash indicator circuit should show a change (battery voltage present or driven to ground depending on design)
- Indicator lamp current: typically small (lamp/LED circuit should draw measurable current; if zero, circuit may be open)
- Continuity: resistance between indicator lamp and ECM harness should be low (near 0 ohms across short connector runs); open = infinite/very high
- Fuse/relay presence: fuse should show battery voltage on both sides; relay contacts should close when energized
- No command: ECM output may be high-impedance; when commanded, ECM output will switch (observe voltage change with respect to ground)
Diagnostic algorithm
- Verify the code with a scan tool, note freeze-frame and related codes (e.g., other glow-plug or power-relay faults).
- Perform a visual inspection of the dash lamp, lamp socket, wiring harness, fuses and relays associated with the glow/heater indicator and preheat system.
- Check the indicator lamp operation by applying battery voltage directly to the lamp socket (confirm the lamp itself is not open).
- Inspect and test fuses and relays: replace any blown fuses and swap or bench-test relays if required.
- With a DVOM, back-probe the indicator circuit at the lamp connector and at the ECM connector. Command the preheat via scan tool (or turn key to preheat) and observe for expected switching (voltage appearing or dropping to ground).
- If no voltage change, check continuity between the lamp and ECM. Repair any open wires, corroded connectors, or poor grounds found.
- If continuity is good and the lamp is functional, test the ECM output driver for switching. If the ECM does not command the output but other systems are normal, suspect ECM output failure and consult manufacturer procedures before replacement.
- After repairs, clear codes and verify proper operation through multiple key cycles and a cold-start check. Re-scan to confirm the code does not return.
Likely causes
- Loose or disconnected connector at indicator lamp or ECM
- Open fuse or stuck/failed relay in the glow/heater circuit
- Broken wire harness (chafing, corrosion, terminal pulled out)
- Bad indicator lamp (bulb or LED cluster) or internal lamp circuit open
- Failed ECM output transistor for the lamp
Fault status
Status
P0381 — Glow Plug/Heater Indicator Control Circuit/Open. ECM detected an open circuit in the glow plug/heater indicator control wiring or components (lamp, fuse, relay, connector, or ECM driver).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
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Code
P0381
HUMMER
P — Powertrain
Glow Plug/Heater Indicator Circuit Malfunction
Views:
UK: 15
EN: 54
RU: 22
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring in the indicator control circuit
- Blown fuse or faulty relay for glow plug/heater indicator
- Faulty indicator lamp (burned out bulb or LED) or lamp connector
- Corroded or poor ground
- Damaged connector or pin (terminal loss of continuity)
- Faulty ECM/PCM driver output (rare)
Symptoms
- Glow-plug/preheat indicator (dash lamp) does not illuminate at key-on preheat
- Longer cranking time or harder cold starts (if driver does not activate glow sequence normally)
- Possible illumination of MIL or stored fault in engine control module
- No visual preheat countdown or incorrect preheat behavior displayed
What to check
- Use a scan tool to confirm P0381 is current and review freeze-frame data
- Visually inspect wiring, connectors, and ground points for damage or corrosion
- Check related fuses and relays for the glow/heater and instrument cluster
- Verify the dash indicator lamp works by applying battery voltage at the lamp connector
- Measure voltage at the lamp connector during a glow request (key ON preheat) and check for continuity to the ECM
- Perform a wiggle test on harness and connectors while monitoring lamp operation and any code responses
Signal parameters
- With ignition ON and preheat requested: dash indicator circuit should show a change (battery voltage present or driven to ground depending on design)
- Indicator lamp current: typically small (lamp/LED circuit should draw measurable current; if zero, circuit may be open)
- Continuity: resistance between indicator lamp and ECM harness should be low (near 0 ohms across short connector runs); open = infinite/very high
- Fuse/relay presence: fuse should show battery voltage on both sides; relay contacts should close when energized
- No command: ECM output may be high-impedance; when commanded, ECM output will switch (observe voltage change with respect to ground)
Diagnostic algorithm
- Verify the code with a scan tool, note freeze-frame and related codes (e.g., other glow-plug or power-relay faults).
- Perform a visual inspection of the dash lamp, lamp socket, wiring harness, fuses and relays associated with the glow/heater indicator and preheat system.
- Check the indicator lamp operation by applying battery voltage directly to the lamp socket (confirm the lamp itself is not open).
- Inspect and test fuses and relays: replace any blown fuses and swap or bench-test relays if required.
- With a DVOM, back-probe the indicator circuit at the lamp connector and at the ECM connector. Command the preheat via scan tool (or turn key to preheat) and observe for expected switching (voltage appearing or dropping to ground).
- If no voltage change, check continuity between the lamp and ECM. Repair any open wires, corroded connectors, or poor grounds found.
- If continuity is good and the lamp is functional, test the ECM output driver for switching. If the ECM does not command the output but other systems are normal, suspect ECM output failure and consult manufacturer procedures before replacement.
- After repairs, clear codes and verify proper operation through multiple key cycles and a cold-start check. Re-scan to confirm the code does not return.
Likely causes
- Loose or disconnected connector at indicator lamp or ECM
- Open fuse or stuck/failed relay in the glow/heater circuit
- Broken wire harness (chafing, corrosion, terminal pulled out)
- Bad indicator lamp (bulb or LED cluster) or internal lamp circuit open
- Failed ECM output transistor for the lamp
Fault status
Status
P0381 — Glow Plug/Heater Indicator Control Circuit/Open. ECM detected an open circuit in the glow plug/heater indicator control wiring or components (lamp, fuse, relay, connector, or ECM driver).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for HUMMER
69
Browse 69 HUMMER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
HUMMER
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Code
P0381
LAND ROVER
P — Powertrain
Malfunction of the glow plug indicator circuit
Views:
UK: 16
EN: 50
RU: 20
AI status
Completed
Completed
100%
Causes
- Broken or disconnected wiring in the indicator control circuit
- Blown fuse or faulty relay for glow plug/heater indicator
- Faulty indicator lamp (burned out bulb or LED) or lamp connector
- Corroded or poor ground
- Damaged connector or pin (terminal loss of continuity)
- Faulty ECM/PCM driver output (rare)
Symptoms
- Glow-plug/preheat indicator (dash lamp) does not illuminate at key-on preheat
- Longer cranking time or harder cold starts (if driver does not activate glow sequence normally)
- Possible illumination of MIL or stored fault in engine control module
- No visual preheat countdown or incorrect preheat behavior displayed
What to check
- Use a scan tool to confirm P0381 is current and review freeze-frame data
- Visually inspect wiring, connectors, and ground points for damage or corrosion
- Check related fuses and relays for the glow/heater and instrument cluster
- Verify the dash indicator lamp works by applying battery voltage at the lamp connector
- Measure voltage at the lamp connector during a glow request (key ON preheat) and check for continuity to the ECM
- Perform a wiggle test on harness and connectors while monitoring lamp operation and any code responses
Signal parameters
- With ignition ON and preheat requested: dash indicator circuit should show a change (battery voltage present or driven to ground depending on design)
- Indicator lamp current: typically small (lamp/LED circuit should draw measurable current; if zero, circuit may be open)
- Continuity: resistance between indicator lamp and ECM harness should be low (near 0 ohms across short connector runs); open = infinite/very high
- Fuse/relay presence: fuse should show battery voltage on both sides; relay contacts should close when energized
- No command: ECM output may be high-impedance; when commanded, ECM output will switch (observe voltage change with respect to ground)
Diagnostic algorithm
- Verify the code with a scan tool, note freeze-frame and related codes (e.g., other glow-plug or power-relay faults).
- Perform a visual inspection of the dash lamp, lamp socket, wiring harness, fuses and relays associated with the glow/heater indicator and preheat system.
- Check the indicator lamp operation by applying battery voltage directly to the lamp socket (confirm the lamp itself is not open).
- Inspect and test fuses and relays: replace any blown fuses and swap or bench-test relays if required.
- With a DVOM, back-probe the indicator circuit at the lamp connector and at the ECM connector. Command the preheat via scan tool (or turn key to preheat) and observe for expected switching (voltage appearing or dropping to ground).
- If no voltage change, check continuity between the lamp and ECM. Repair any open wires, corroded connectors, or poor grounds found.
- If continuity is good and the lamp is functional, test the ECM output driver for switching. If the ECM does not command the output but other systems are normal, suspect ECM output failure and consult manufacturer procedures before replacement.
- After repairs, clear codes and verify proper operation through multiple key cycles and a cold-start check. Re-scan to confirm the code does not return.
Likely causes
- Loose or disconnected connector at indicator lamp or ECM
- Open fuse or stuck/failed relay in the glow/heater circuit
- Broken wire harness (chafing, corrosion, terminal pulled out)
- Bad indicator lamp (bulb or LED cluster) or internal lamp circuit open
- Failed ECM output transistor for the lamp
Fault status
Status
P0381 — Glow Plug/Heater Indicator Control Circuit/Open. ECM detected an open circuit in the glow plug/heater indicator control wiring or components (lamp, fuse, relay, connector, or ECM driver).
Repair difficulty: Medium
Diagnostic time: 0.5-2.0 hours
Similar codes
Repair manuals
Manual library for LAND ROVER
160
Browse 160 LAND ROVER manuals: repair procedures, diagnostics, wiring diagrams, component locations, service data and Labor Times by year, model and trim.
LAND ROVER
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LAND ROVER: 2023
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Range Rover Velar
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LAND ROVER: 2022
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Discovery Sport
-
Range Rover
- Autobiography, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover Autobiography
- 2022 Range Rover Base
- First Edition
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2022: Range Rover HSE Westminster
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2022: Range Rover SE
- SE, 4.4L Eng VIN 7 · 4.4L Eng VIN 72022: Range Rover SE
- SV
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
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Range Rover Evoque
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Range Rover Sport
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Range Rover Velar
-
LAND ROVER: 2021
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Discovery Sport
-
Range Rover
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Autobiography
- Autobiography Fifty Edition
- 2021 Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover HSE
- HSE Westminster, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover HSE Westminster
- HSE Westminster, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover HSE Westminster
- SVAutobiography
- SVAutobiography Dynamic
- SVAutobiography Dynamic Blk.
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography
- Autobiography, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2021: Range Rover Sport Autobiography Dynamic
- HSE Dynamic
- HSE Silver Edition, 2.0L Eng VIN Y · 2.0L Eng VIN Y2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN K · 3.0L Eng VIN K2021: Range Rover Sport HSE Silver Edition
- HSE Silver Edition, 3.0L Eng VIN U · 3.0L Eng VIN U2021: Range Rover Sport HSE Silver Edition
- HST
- SE
- SVR
- SVR Carbon Edition
-
Range Rover Velar
-
LAND ROVER: 2020
-
Discovery
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE
- HSE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE
- HSE Luxury, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery HSE Luxury
- HSE Luxury, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery HSE Luxury
- Landmark
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Discovery SE
- SE, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Discovery SE
-
Discovery Sport
-
Range Rover
- Autobiography
- Base, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Base
- Base, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Base
- HSE, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover HSE
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover HSE
- SVAutobiography
- SVAutobiography Dynamic
-
Range Rover Evoque
-
Range Rover Sport
- Autobiography Dynamic, 2.0L Eng VIN Y · 2.0L Eng VIN Y2020: Range Rover Sport Autobiography Dynamic
- Autobiography Dynamic, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport Autobiography Dynamic
- HSE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport HSE
- HSE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport HSE
- HSE, 5.0L Eng VIN E · 5.0L Eng VIN E2020: Range Rover Sport HSE
- HSE Dynamic
- HSE PHEV
- HST
- SE, 3.0L Eng VIN K · 3.0L Eng VIN K2020: Range Rover Sport SE
- SE, 3.0L Eng VIN U · 3.0L Eng VIN U2020: Range Rover Sport SE
- SVR
-
Range Rover Velar
- R-Dynamic HSE
- R-Dynamic S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar R-Dynamic S
- R-Dynamic S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar R-Dynamic S
- S, 2.0L Eng VIN X · 2.0L Eng VIN X2020: Range Rover Velar S
- S, 3.0L Eng VIN V · 3.0L Eng VIN V2020: Range Rover Velar S
- SVAutobiography Dyn.
-
LAND ROVER: 2019
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