TDI Glow Plug Reference
Complete glow plug specifications, part numbers, testing procedures, and replacement guide covering every VW TDI generation from ALH to EA288.
How TDI Glow Plugs Work
FundamentalsPurpose
- FunctionPre-heat combustion chamber
- Operating Temp800-1000°C tip temp
- Heat-up Time2-5 seconds (modern)
- Post-GlowUp to 3 min after start
- Voltage4.4V-11V (varies by type)
Types Used in VW TDI
- ALH/AHUStandard rod-type
- BEW/BRMFast-heat ceramic
- CBEA/CJAAInstant-heat ceramic
- CRUA/EA288Ceramic + pressure sensor
- EA288evoPressure sensor on cyl 3
Unlike gasoline engines that use spark plugs, diesel engines rely on compression ignition. In cold weather, the cylinder walls absorb heat from the compressed air, potentially dropping temps below the diesel fuel's ignition point (~210°C). Glow plugs pre-heat the combustion chamber to ensure reliable cold starting. Failed glow plugs cause hard starting, white smoke, rough idle, and increased emissions during warm-up.
Glow Plug Part Numbers by Engine
Parts Reference| Engine Code | Generation | OEM VW Part # | Bosch Part # | NGK Part # | Beru Part # | Resistance | Torque |
|---|---|---|---|---|---|---|---|
| ALH | VP37 | N 105 912 01 | 0 250 202 032 | Y-741U | GN963 | 0.5-0.8Ω | 15 Nm |
| AHU/1Z | VP37 | N 105 912 01 | 0 250 202 032 | Y-741U | GN963 | 0.5-0.8Ω | 15 Nm |
| BEW | PD | N 105 913 07 | 0 250 403 009 | CZ262 | GE100 | 0.3-0.5Ω | 15 Nm |
| BRM | PD | N 105 913 07 | 0 250 403 009 | CZ262 | GE100 | 0.3-0.5Ω | 15 Nm |
| BHW | PD | 070 963 319 E | 0 250 403 011 | CZ272 | GE105 | 0.3-0.5Ω | 15 Nm |
| CBEA | CR | 059 963 319 S | 0 250 403 014 | CZ303 | GE115 | <0.3Ω | 15 Nm |
| CJAA | CR | 059 963 319 S | 0 250 403 014 | CZ303 | GE115 | <0.3Ω | 15 Nm |
| CKRA | CR | 059 963 319 S | 0 250 403 014 | CZ303 | GE115 | <0.3Ω | 15 Nm |
| CRUA | EA288 | 04L 963 319 C | 0 250 403 024 | CZ541 | GE130 | <0.3Ω | 15 Nm |
Even if only one glow plug has failed, replace all four simultaneously. Glow plugs degrade at similar rates. Mismatched plugs cause uneven cylinder heating, rough starting, and accelerated wear on the remaining new plug. The cost difference between one and four plugs is minimal compared to the labor of doing the job twice.
Glow Plug Control Systems
ElectronicsALH / 1Z / AHU (1996-2003)
- ControllerRelay J52 (glow plug relay)
- LocationRelay panel above fuse box
- ControlSimple relay, ECU-timed
- Pre-glow Time5-12 sec (temp dependent)
- Post-glowUp to 60 seconds
- Failure ModeRelay contacts burn/weld
BEW/BRM/BHW (2004-2006)
- ControllerJ179 (glow plug control unit)
- LocationOn engine, near glow plugs
- ControlPWM modulated, CAN bus
- Pre-glow Time2-5 sec (ceramic plugs)
- Post-glowUp to 180 seconds
- Failure ModeModule corrosion, CAN faults
CBEA/CJAA (2009-2014)
- ControllerJ179 (integrated module)
- LocationEngine-mounted module
- ControlPWM with current feedback
- Pre-glow Time1-3 sec (instant-heat)
- Post-glowUp to 180 seconds
- Intermediate GlowActivates during driving
EA288/EA288evo (2015+)
- ControllerIntegrated in ECU
- Special FeaturePressure sensor on cyl 3
- ControlIndividual cylinder PWM
- Pre-glow Time<2 seconds
- Post-glowContinuous during warm-up
- Combustion MonitoringReal-time via pressure plug
Testing Glow Plugs
DiagnosticsMethod 1: Resistance Test (Plugs Removed)
Remove Glow Plug Connector
Disconnect the bus bar or individual connectors from all four glow plugs. On ALH engines, this is a single bus bar with nuts. On PD and CR engines, individual connectors.
Set Multimeter to Ohms
Place one probe on the glow plug terminal (center post) and the other on the engine block (ground). A good plug reads 0.3-0.8Ω depending on type. OL (open) or >5Ω means the plug is dead.
Compare All Four
All four should read within 0.1Ω of each other. One significantly higher reading indicates a failing plug even if not fully open.
Method 2: Current Draw Test (In-Situ)
Clamp Ammeter on Glow Plug Wire
Use a DC clamp meter around the wire feeding each glow plug. With the glow plug system activated (key ON, wait for glow plug light to go out).
Measure Initial Current Draw
Each plug should draw 15-25 amps initially, dropping to 8-12 amps as it heats. A plug drawing zero amps is open. Significantly lower current indicates partial failure.
Check Total Circuit Draw
Total draw for all four plugs should be 60-100A initially. The glow plug relay/module must handle this current. Weak relays cause all plugs to underperform.
Method 3: VCDS/OBD Scan
Check Fault Codes
Common glow plug DTCs: P0380 (glow plug circuit A), P0381 (glow plug indicator circuit), P0670 (glow plug control module), P0671-P0674 (individual cylinder glow plug circuits 1-4).
VCDS Measuring Blocks
On ALH: Block 013 shows glow plug duration. On PD/CR: Advanced Measuring Values show individual cylinder glow plug status and current draw in real-time.
ALH glow plugs are notorious for seizing in the cylinder head due to carbon buildup around the plug body. Never force a glow plug out. Soak with penetrating oil for 24+ hours. Run the engine to operating temperature first. Use a 12-point deep socket, not a 6-point. If a plug snaps, the head must be removed for extraction. Prevention: apply anti-seize (ceramic-based, NOT copper) to the threads during installation and replace every 80,000 miles proactively.
Replacement Procedures by Engine
How-ToALH (1.9 TDI VP37) - Difficulty: Easy
- AccessRemove engine cover
- Tool10mm deep socket (12-pt)
- Bus Bar Nuts4 Nm
- Glow Plug Torque15 Nm
- Anti-SeizeCeramic on threads
- Time30-60 min (if not seized)
- HazardHigh seizure risk at 100k+
BEW/BRM (1.9 TDI PD) - Difficulty: Easy
- AccessRemove engine cover
- Tool10mm deep socket (12-pt)
- Connector TypeIndividual push-on
- Glow Plug Torque15 Nm
- Anti-SeizeCeramic on threads
- Time30-45 min
- NoteLess seizure-prone than ALH
CBEA/CJAA (2.0 TDI CR) - Difficulty: Moderate
- AccessRemove intake manifold
- Tool10mm deep socket + extensions
- Connector TypeIndividual clip-on
- Glow Plug Torque15 Nm
- Time1-2 hours
- NoteIntake manifold removal adds time
CRUA/EA288 (2.0 TDI) - Difficulty: Moderate
- AccessRemove intake components
- Special PlugCyl 3 has pressure sensor
- Pressure Plug #Different part number
- Glow Plug Torque15 Nm
- CodingVCDS coding may be needed
- Time1-2 hours
- CostPressure sensor plug is $$$
Failure Symptoms & Diagnosis
Troubleshooting| Symptom | 1 Plug Failed | 2+ Plugs Failed | Relay/Module Failed |
|---|---|---|---|
| Hard cold start | Slight hesitation | Extended cranking | No start below 40°F |
| White smoke at startup | Brief puff | Heavy for 30-60 sec | Heavy until warm |
| Rough idle when cold | Slight miss | Pronounced shake | Severe shaking |
| Check engine light | Sometimes | Usually | Always |
| Warm start affected? | No | No | No |
| Glow plug light behavior | Normal | Normal | No light / stays on |
A single failed glow plug may go completely unnoticed in warm climates (above 60°F/15°C). The problem only becomes apparent in cold weather when the remaining three plugs can't compensate. If you live in a cold climate, proactive replacement every 80,000-100,000 miles prevents cold morning no-starts.
Diagnostic Trouble Codes
Fault Codes| DTC Code | Description | Common Cause | Fix |
|---|---|---|---|
| P0380 | Glow Plug/Heater Circuit A | Failed relay J52 or wiring | Test relay, check bus bar connections |
| P0381 | Glow Plug Indicator Circuit | Dash indicator wiring fault | Check instrument cluster connection |
| P0670 | Glow Plug Control Module | J179 module failure | Replace glow plug control module |
| P0671 | Cylinder 1 Glow Plug Circuit | Failed glow plug or wiring | Test plug resistance, check connector |
| P0672 | Cylinder 2 Glow Plug Circuit | Failed glow plug or wiring | Test plug resistance, check connector |
| P0673 | Cylinder 3 Glow Plug Circuit | Failed glow plug or wiring | Test plug resistance, check connector |
| P0674 | Cylinder 4 Glow Plug Circuit | Failed glow plug or wiring | Test plug resistance, check connector |
| P0683 | Glow Plug Control Module to ECM Communication | CAN bus fault between J179 and ECU | Check CAN wiring, module ground |