Trouble Code PO673 Cylinder 3 Glow Plug Circuit

DTC P0671: Cylinder #1 Glow Plug Control Circuit
DTC P0672: Cylinder #2 Glow Plug Control Circuit
DTC P0673: Cylinder #3 Glow Plug Control Circuit
DTC P0674: Cylinder #4 Glow Plug Control Circuit
DTC P0675: Cylinder #5 Glow Plug Control Circuit
DTC P0676: Cylinder #6 Glow Plug Control Circuit
DTC P0677: Cylinder #7 Glow Plug Control Circuit
DTC P0678: Cylinder #8 Glow Plug Control Circuit

Circuit/System Description
The glow plug controller has the ability to perform internal checks, an open or a short to ground on each of the glow plug circuits. If the glow plug controller senses a problem in a glow plug circuit, the glow plug on the affected cylinder will be disabled and the glow plug controller will send an error message to the engine control module (ECM). If this condition exists, the DTC will set.
Conditions for Setting the DTC
The glow plug controller detects that the glow plug control circuit is open, shorted to ground, or has more than 1 ohm of resistance.

Circuit/System Verification
Verify that DTC P064C is not set.
If DTC P064C is set, refer to DTC P064C.
Ignition ON, engine OFF, observe the scan tool Glow Plug 1-Glow Plug 8 parameters. All 8 Glow Plug parameters should closely match each other.
Refer to Testing for Intermittent Conditions and Poor Connections if you cannot duplicate the conditions.
Engine running, observe the DTC information with a scan tool. DTCs P0671-P0678 should not set.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.

DTC C0035 Left Front Wheel Speed Sensor Circuit
DTC C0201 Antilock Brake System (ABS) Enable Relay Contact Circuit
The system relay, located within the electronic brake control module (EBCM), supplies battery voltage to all of the valve solenoids and to the ABS pump motor. When the relay contacts close, the EBCM monitors the voltage supplied to the valve solenoids and compares this voltage to monitored ignition voltage.

Error Code: P0404
Fault Location:
Exhaust Gas Recirculation (EGR) System - Range/Performance Problem
Causes:
-Hose leak/blockage.
-Wiring harness.
-Exhaust gas recirculation (EGR) valve/solenoid.
Error Code: P0473
Discription:
Exhaust Gas Pressure Sensor - High Input
Causes:
- Wiring short to positive.
- Exhaust gas pressure sensor (G450).
- Engine control module (ECM).
Error Code: P0674
Description:
Glow Plug Cylinder 4 Circuit - Circuit Malfunction
Causes:
-No Pre-Glow Period.
-Poor Cold Starting.
-Glow Plug Wiring faulty.
-Poor connection.
-Relay.
-Glow plug control module.
-Glow Plug faulty.
-Engine control module (ECM).
Solutions:
Check Glow Plug Wiring.
Check Glow Plug.
Error Code: P0675
Description:
Glow Plug Cylinder 5 Circuit - Circuit Malfunction
Causes:
-No Pre-Glow Period.
-Poor Cold Starting.
-Glow Plug Wiring faulty.
-Poor connection.
-Relay.
-Glow plug control module.
-Glow Plug faulty.
-Engine control module (ECM).
Solutions:
-Check Glow Plug Wiring.
-Check Glow Plug.

HI,
http://engine-codes.com/p0671_gmc.html

It's a Glow Plug.

Possible causes- Cylinder #1 glow plug circuit is open or shorted
- Faulty cylinder #1 glow plug
- Faulty glow plug module Help with thisSymptoms- Engine Light ON (or Service Engine Soon Warning Light)
- Lack/Loss of Power
- The engine may be harder to start
- Engine hesitation

Read more: http://engine-codes.com/p0671_gmc.html#ixzz28UT1VO75

OBD Code P0673refers to
The Engine Control Module (ECM) has detected a fault in the cylinder #3 glow plug circuit SymptomsPossible sumptoms of OBD code P0673
- Engine Light ON (or Service Engine Soon Warning Light) - Lack/Loss of Power - The engine may be harder to start - Engine hesitation CausesPossible causes of OBD code P0673
- Cylinder #3 glow plug circuit is open or shorted - Faulty cylinder #3 glow plug - Faulty glow plug module

Hi.

The glow plugs are plugged into the cylinders. They basically do the same that spark plugs do in gasoline/petrol fueled engines.

It is quite rare that glow plugs heater circuits go bad all at once. Test also the wiring harness.

Here a forum that can help you a lot. Picture below is from the tdiclub.com forum in this link:

The code P0674 tells you that something in the glow plug circuit is faulty causing the glow plug on cylinder #4 to fail to heat up. The entire circuit must be checked to locate the fault.

Symptoms With just one glow plug failure other than the check engine light coming on, the symptoms will be minimal since the engine will normally start with one bad plug, under freezing conditions you would be more likely to experience hard starting.

Potential Causes The causes for this DTC may include: Faulty cylinder #4 glow plug Open or shorted glow plug circuit Damaged wiring connector Faulty glow plug control module Diagnostic Steps & Possible Solutions You will need a digital volt ohm meter (DVOM) for the complete test.
Continue through the tests until the problem is confirmed. You will also need a basic OBD code scanner to reset the computer and erase the code. Check the cylinder #4 glow plug by disconnecting the wire connector on the plug. Place the DVOM on ohms and place the red lead on the glow plug terminal and the black lead on a good ground. The range is .5 to 2.0 ohms, if it is out of range replace the glow plug.

If you have replaced the glow plugs....replace glow plug harness. If code reappears, replace glow plug controller.

FYI: VW numbers the glow plugs backwards. IE: #1 cylinder next to the timing belt cover is number #4 glow plug...so your #2 is actually #3 on the engine.

p1111 System Pass (No DTCs Available)
P0107 BARO Circuit Low Input
P0l08 BARO Circuit High Input
P0112 IAT Sensor Circuit Low Input
P0113 IAT Sensor Circuit High Input
P0122 Accelerator Pedal Sensor Circuit Low Input
P0123 Accelerator Pedal Sensor Circuit High Input
P0197 EOT Sensor Circuit Low Input
P0198 EOT Sensor Circuit High Input
P0220 Throttle Switch B Circuit Malfunction
P0221 Throttle Switch B Circuit Performance
P0230 Fuel Pump Relay Driver Fail
P0231 Fuel Pump Relay Driver Circuit Failure
P0232 Fuel Pump Relay Driver Failed Off
P0236 Turbo Boost Sensor A Circuit Performance
P0237 Turbo Boost Sensor A Circuit Low Input
P0238 Turbo Boost Sensor A Circuit High Input
P0261 Injector Circuit Low - Cylinder 1
P0262 Injector Circuit High - Cylinder 1
P0263 Cylinder 1 Contribution/Balance Fault
P0264 Injector Circuit Low - Cylinder 2
P0265 Injector Circuit High - Cylinder 2
P0266 Cylinder 2 Contribution/Balance Fault
P0267 Injector Circuit Low - Cylinder 3
P0268 Injector Circuit High - Cylinder 3
P0269 Cylinder 3 Contribution/Balance Fault
P0270 Injector Circuit Low - Cylinder 4
P0271 Injector Circuit High - Cylinder 4
P0272 Cylinder 4 Contribution/Balance Fault
P0273 Injector Circuit Low - Cylinder 5
P0274 Injector Circuit High - Cylinder 5
P0275 Cylinder 5 Contribution/Balance Fault
P0276 Injector Circuit Low - Cylinder 6
P0277 Injector Circuit High - Cylinder 6
P0278 Cylinder 6 Contribution/Balance Fault
PO279 Injector Circuit Low - Cylinder 7
P0280 Injector Circuit High - Cylinder 7
P0281 Cylinder 7 Contribution/Balance Fault
P0282 Injector Circuit Low - Cylinder 8
P0283 Injector Circuit High - Cylinder 8
P0284 Cylinder 8 Contribution/Balance Fault
P0301 Fault Cylinder A-Misfire Detected (CYL 1)
P0302 Fault Cylinder B-Misfire Detected (CYL2)
P0303 Fault Cylinder D-Nlisfire Detected (CYL 3)
P0304 Fault Cylinder E-Misfire Detected (CYL 4)
P0305 Fault Cylinder F-Misfire Detected (CYL5)
P0306 Fault Cylinder G-Nlisfire Detected (CYL 6)
P0307 Fault Cylinder C-Misfire Detected (CYL 7)
P0308 Fault Cylinder H-Misfire Detected (CYL 8)
P0340 CMP Sensor Circuit Malfunction
P0341 CMP Sensor Circuit Performance
P0344 CMP Sensor Circuit Intermittent
P0360 Glow Plug Circuit Malfunction
P0381 Glow Plug Indicator Circuit Malfunction
P0460 Fuel Tank Level Indicator Circuit Malfunction
P0470 Exhaust Back Pressure Sensor Circuit Malfunction
P0471 Exhaust Back Pressure Sensor Circuit Performance
P0472 Exhaust Back Pressure Sensor Circuit Low Input
P0473 Exhaust Back Pressure Sensor Circuit High Input
P0476 Exhaust Pressure Control Valve Maffunction
P0476 Exhaust Pressure Control Valve Performance
P0478 Exhaust Pressure Control Valve High Input
P0500 Vehicle Speed Sensor (VSS) Malfunction
P0503 Vehicle Speed Sensor Noisy
PO541 Manifold Intake Air Heater
P0542 Manifold Intake Air Heater
P0560 System Voltage Malfunction
P0662 System Voltage Low
P0563 System Voltage High
P0666 Cruise 'On" Signal Malfunction
P0566 Cruise "Off' Signal Malfunction
P0667 Cruise 'Resume' Signal Malfunction
P0668 Cruise "Set' Signal Malfunction
P0669 Cruise "Coast' Signal Malfunction
P0571 Brake Svdtch A Circuit Malfunction
P0603 Internal Control Module KAM Error
P0605 Internal Control Module ROM Error
PO606 PCM Processor Fault
P0640 Manifold Intake Air Heater
P0670 Glow plug control circuit malfunction
P0671 Glow plug #1 circuit failure
P0672 Glow plug #2 circuit failure
P0673 Glow plug #3 circuit failure
P0674 Glow plug #4 circuit failure
P0675 Glow plug #5 circuit failure
P0676 Glow plug #6 circuit failure
P0677 Glow plug #7 circuit failure
P0678 Glow plug #8 circuit failure
P0683 Glow plug diagnostic signal communication fault
P0703 Brake Switch B Circuit Malfunction
P0704 Clutch Pedal Position Switch Input Circuit Malfunction
P0705 TR Sensor Circuit Malfunction
P0707 TR Sensor Circuit Low Input
P0708 TR Sensor Circuit High Input
P0712 Transmission Fluid Temp. Sensor CKT Low Input
P0713 Transmission Fluid Temp. Sensor CKT High Input
P0715 TSS Sensor Circuit Malfunction Fault
P0717 TSS Intermittent Failure
P0718 Noisy TSS
P0720 OSS Sensor Circuit Malfunction
P0721 Noisy OSS
P0722 OSS Intermittent Failure
P0732 Gear Two Ratio Error
P0733 Gear Three Ratio Error
P0741 TCC Circuit Performance
P0743 Torque Converter Clutch System Electrical Failure
P0750 Shift Solenoid 1 Malfunction
P0755 Shift Solenoid B Malfunction
P0781 1-2 Shift Malfunction
P0782 2-3 Shift Malfunction
P0783 3-4 Shift Malfunction
P0800 Logon to http://web.archive.org/web/200701120...utoadvice.com/ A.S.A.P
P1000 OBD 11 Monitor Checks Not Complete. More Driving Required
P1105 Dual Alternator Upper Fault (Monitor)
P1106 Dual Afternator Lower Fault (Control)
P1107 Dual Alternator Lower Circuit Malfunction (Control)
P1108 Dual Alternator BATT Lamp Circuit Malfunction
P1118 Manifold Air Temperature Sensor Low Input
P1119 Manifold Air Temperature Sensor High Input
P1139 Water in Fuel Indicator Circuit Malfunction
P1140 Water in Fuel Condition
P1184 Engine Oil Tamp Sensor Circuit Performance
P1209 Injection Control System Pressure Peak Fault
P1210 Injection Control Pressure Above Expected Level
P1211 ICP Not Controllable - Pressure Abow/Below Desired
P1212 ICP Voltage Not at Expected Level
P1218 CID Stuck High
P1219 CID Stuck Low
P1247 Turbo Boost Pressure Low
P1248 Turbo Boost Pressure Not Detected
P1249 Wastagate Fail Steady State Test
P1250 Electronic Passive Anti-Theft System
P1261 High to Low Side Short - Cylinder 1
P1262 High to Low Side Short - Cylinder 2
P1263 High to Low Side Short - Cylinder 3
P1264 High to Low Side Short - Cylinder 4
P1265 High to Low Side Short - Cylinder 5
P1266 High to Low Side Short - Cylinder 6
P1267 High to Low Side Short - Cylinder 7
P1268 High to Low Side Short - Cylinder 8
P1271 High to Low Side Open - Cylinder 1
P1272 High to Low Side Open - Cylinder 2
P1273 High to Low Side Open - Cylinder 3
P1274 High to Low Side Open - Cylinder 4
P1275 High to Low Side Open - Cylinder 5
P1276 High to Low Side Open - Cylinder 6
P1277 High to Low Side Open - Cylinder 7
P1278 High to Low Side Open - Cylinder 8
P1280 ICP Circuit Out of Range Low
P1281 ICP Circuit Out of Range High
P1282 Excessive ICP
P1263 IPR Circuit Failure
P1284 ICP Failure - Aborts KOER or CCT Test
P1291 High Side No. 1 (Right) Short to GND or B
P1292 High Side No. 2 (Left) Short to GND or B
P1293 High Side Open Bank No. 1 (Right)
P1294 High Side Open Bank No. 2 (Left)
P1295 Multiple Faults on Bank No. 1 (Right)
P1296 Multiple Faults on Bank No. 2 (Left)
P1297 High Sides Shorted Together
P1298 IDM Failure
P1316 Injector Circuit/IDM Codes Detected
P1391 Glow Plug Circuit Low Input Bank No. 1(Right)
P1393 Glow Plug Circuit Low Input Bank No. 2 (Left)
P1395 Glow Plug Monitor Fault Bank No. 1
P1396 Glow Plug Monitor Fault Bank No. 2
P1397 SYstem Voltage Out of Self Test Range
P1464 A/C On During KOER or CCT Test
P1501 VSS Out Of Self Test Range
P1502 Invalid Self Test - APCM Functioning
P1531 Invalid Test -Accelerator Pedal Movement
P1536 Parking Brake Applied Failure
P1662 IDM EN Circuit Failure
P1663 FDCS Circuit Failure
P1667 CID Circuit Failure
P1668 PCM -IDM Diagnostic Communication Error
P1670 EF Feedback Signal Not Detected
P1690 Wastegate Control Valve Malfunction
P1702 TRS Sensor Intermittent Circuit Malfunction
P1704 Digital TRS Failed to Transition State
P1705 TR Sensor out of Self Test Range
P1711 TFT Sensor Out of Self Test Range
P1713 TFT Stuck in Range Low-Below 50'F
P1714 Shilt Solenoid A Inductive Signature Malfunction
P1715 Shift Solenoid B Inductive Signature Malfunction
P1718 TFT Stuck in Range High-Above 25OF
P1728 Transmission Slip Error
P1729 4x4L Switch Error
P1744 Torque Converter Clutch System Performance
P1746 EPC Solenoid Open Circuit
P1747 EPC Solenoid Short Circuit
P1754 CCS (Solenoid) Circuit Malfunction
P1760 EPC Solenoid Short Intermittent
P1780 TCS Circuit Out of self Test Range
P1781 4x4L Circuit Out of Self Test Range
P1783 Transmission Overtemperature Condition
No Code No Communication
No Code Auxiliary Powertrain Control System
No Code Tachometer

Above the Relay Panel is the Auxiliary Relay Panel. Has thirteen positions in it.
6 across the top, 7 across the bottom.

Across the bottom the Glow Plug Relay is the fourth one over from the left. It is Number 10.
(180)

You probably need to replace the glow plug harness. The contacts in the boots that connect to the glow plugs get corroded and throw off the resistance of the circuit. The controller in the VW measures whether your glow plugs are good or not by testing the resistance in the circuit. Test all the glow plugs like DickyIV1 stated and if they are all good try cleaning out the crud on the contacts in the glow plug harness. You will then either need to clear the error code or wait several trips for it to clear itself. If it never clears itself or if it comes back on after you clear it then the glow plug harness is too much of a mess. This is really common on the TDIs (mine needs to be changed but i have been putting it off and ignoring the mil light). When I first tried cleaning the harness on my car it didn't give me a problem for another year and a half. But I knew I'd eventually be changing it.
The other thing to keep in mind is that you should change out glow plugs as a set. It causes less problems in the long run since if one failed you will probably find other will soon fail and it keeps all the resistance close to the same value.