2015 VW GTI Engine Trouble After Spark Plug & Coil Change: Fueling Issues Suspected?

Recently, a 2015 Vw Gti owner decided to perform some routine maintenance, replacing the spark plugs and ignition coils to keep their ride running smoothly. The parts chosen were high-quality, OEM-level components:

• OEM NGK RS7 Double Iridium Spark Plugs (OE # 06K905601M)
• Red Top OE 8V RS3 / B9 S4 Ignition Coil Packs

During the installation, it was noted that the D-rings on two of the old coils were brittle, suggesting heat degradation and highlighting the need for replacement. After the new components were installed, an initial 25-minute test drive seemed successful. The engine felt responsive and powerful, providing a noticeable improvement. However, the positive experience was short-lived. Just as the driver was nearing home, the dreaded Engine Control Problem (ECP) light illuminated, and the engine stalled. This sudden issue raised concerns that the spark plug and coil replacement might have inadvertently triggered another problem.

Further investigation using a VCDS diagnostic tool revealed a new set of fault codes, pointing towards potential fueling issues. This was unexpected, as the initial intention was simply preventative maintenance on the ignition system. The new codes suggest that the problem might not be related to the recently replaced ignition components, but rather to the fuel delivery system. It’s possible the spark plugs and coils were not the root cause of any underlying issue, but simply a coincidence that problems surfaced after their replacement.

Interestingly, the owner recalled that the fuel pump had been replaced under a recall in the past. This brings up the possibility of a recurring fuel pump failure, especially since there might be an active recall again for similar models. Another potential culprit could be the fuel injectors.

To get to the bottom of this issue and properly diagnose the 2015 VW GTI, the key question now is how to differentiate between a failing fuel pump and problematic fuel injectors. Determining the exact cause will be crucial for effective repair and getting this GTI back on the road.

Here are the detailed fault codes retrieved from the VCDS scan:

Sunday,07,April,2024,19:39:40:31634 VCDS -- Windows Based VAG/VAS Emulator Running on Windows 11 x64 VCDS Version: 23.11.0.0 (x64) Data version: 20231027 DS351.0 www.Ross-Tech.com Dealer/Shop Name: Larry V Home VIN: 3VW447AU9FM079073 License Plate: Mileage: 152043 Repair Order: -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Address 01: Engine Labels: 06K-907-425-V1.clb Control Module Part Number: 5G0 906 259 A HW: 06K 907 425 B Component and/or Version: 2.0l R4 TFSI H13 0006 Software Coding: 091D00124424002F1000 Work Shop Code: WSC 00066 790 00149 ASAM Dataset: EV_ECM20TFS0205G0906259A 001008 (VW37) ROD: EV_ECM20TFS0205G0906259A.rod VCID: 2C5C16AA4770A5F14F-8078 7 Faults Found: 17387 - Monitoring of Fuel Injector for Cylinder 1 P10B1 00 [00101100] - Malfunction Detected Intermittent - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 5 Mileage: 244647 km Date: 2024.03.29 Time: 10:28:32 Engine RPM: 1285.25 /min Normed load value: 21.2 % Vehicle speed: 17 km/h Coolant temperature: 101 C Intake air temperature: 56 C Ambient air pressure: 1020 mbar Voltage terminal 30: 13.535 V Unlearning counter according OBD: 40 Engine: operating status: PL STATE_LS_SAE[1]: CL T_AST_SAE: 26 s MAP_MES_SAE: 75 kPa Lambda probe voltage: bank 1: probe 1 (broadband probe): 1.870 V FAC_TPS_1_SAE: 18.359375 % FUP_H_SAE: 12870.0 kPa 17355 - Injector: Cylinder 1 (N30) P0201 00 [10101100] - Circuit Malfunction MIL ON - Intermittent - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 2 Mileage: 244667 km Date: 2024.03.29 Time: 11:42:03 Engine RPM: 737.50 /min Normed load value: 8.2 % Vehicle speed: 0 km/h Coolant temperature: 104 C Intake air temperature: 52 C Ambient air pressure: 1020 mbar Voltage terminal 30: 11.406 V Unlearning counter according OBD: 40 Engine: operating status: IS STATE_LS_SAE[1]: CL T_AST_SAE: 0 s MAP_MES_SAE: 34 kPa Lambda probe voltage: bank 1: probe 1 (broadband probe): 2.104 V FAC_TPS_1_SAE: 11.718750 % FUP_H_SAE: 8590.0 kPa 15125 - Cylinder 1 P0301 00 [11101101] - Misfire Detected MIL ON - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 2 Mileage: 244667 km Date: 2024.03.29 Time: 11:42:37 Engine RPM: 1891.25 /min Normed load value: 22.4 % Vehicle speed: 26 km/h Coolant temperature: 103 C Intake air temperature: 51 C Ambient air pressure: 1010 mbar Voltage terminal 30: 13.671 V Unlearning counter according OBD: 40 Engine: operating status: PL STATE_LS_SAE[1]: OL_ERR T_AST_SAE: 28 s Engine oil temperature: 109.0 C Lambda probes actual: bank1: 1.2871 FAC_LAM_LIM[1]: 0.000 % FUP_H_SAE: 15280.0 kPa 15131 - Cylinder 3 P0303 00 [11101101] - Misfire Detected MIL ON - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 1 Mileage: 244694 km Date: 2024.04.06 Time: 18:17:15 Engine RPM: 1891.25 /min Normed load value: 22.4 % Vehicle speed: 26 km/h Coolant temperature: 103 C Intake air temperature: 51 C Ambient air pressure: 1010 mbar Voltage terminal 30: 13.671 V Unlearning counter according OBD: 40 Engine: operating status: PL STATE_LS_SAE[1]: OL_ERR T_AST_SAE: 28 s Engine oil temperature: 109.0 C Lambda probes actual: bank1: 1.2871 FAC_LAM_LIM[1]: 0.000 % FUP_H_SAE: 15280.0 kPa 15134 - Cylinder 4 P0304 00 [01100101] - Misfire Detected Not Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 1 Mileage: 244694 km Date: 2024.04.06 Time: 18:19:21 Engine RPM: 823.75 /min Normed load value: 16.1 % Vehicle speed: 0 km/h Coolant temperature: 105 C Intake air temperature: 58 C Ambient air pressure: 1010 mbar Voltage terminal 30: 14.042 V Unlearning counter according OBD: 40 Engine: operating status: IS STATE_LS_SAE[1]: OL_ERR T_AST_SAE: 16 s Engine oil temperature: 107.0 C Lambda probes actual: bank1: 1.2158 FAC_LAM_LIM[1]: 0.000 % FUP_H_SAE: 11130.0 kPa 15128 - Cylinder 2 P0302 00 [01100101] - Misfire Detected Not Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 2 Mileage: 244667 km Date: 2024.03.29 Time: 11:42:37 Engine RPM: 1891.25 /min Normed load value: 22.4 % Vehicle speed: 26 km/h Coolant temperature: 103 C Intake air temperature: 51 C Ambient air pressure: 1010 mbar Voltage terminal 30: 13.671 V Unlearning counter according OBD: 40 Engine: operating status: PL STATE_LS_SAE[1]: OL_ERR T_AST_SAE: 28 s Engine oil temperature: 109.0 C Lambda probes actual: bank1: 1.2871 FAC_LAM_LIM[1]: 0.000 % FUP_H_SAE: 15280.0 kPa 15137 - Random/Multiple Cylinder Misfire Detected P0300 00 [11101101] - - MIL ON - Confirmed - Tested Since Memory Clear Freeze Frame: Fault Priority: 2 Fault Frequency: 2 Mileage: 244667 km Date: 2024.03.29 Time: 11:42:37 Engine RPM: 1891.25 /min Normed load value: 22.4 % Vehicle speed: 26 km/h Coolant temperature: 103 C Intake air temperature: 51 C Ambient air pressure: 1010 mbar Voltage terminal 30: 13.671 V Unlearning counter OBD: 40 Engine: operating status: PL STATE_LS_SAE[1]: OL_ERR T_AST_SAE: 28 s Engine oil temperature: 109.0 C Lambda probes actual: bank1: 1.2871 FAC_LAM_LIM[1]: 0.000 % FUP_H_SAE: 15280.0 kPa Readiness: 0000 0000 -------------------------------------------------------------------------------- -------------------------------------------------------------------------------- Address 01: DTCs cleared

The fault codes retrieved are:

• P10B1 (17387): Monitoring of Fuel Injector for Cylinder 1 – Malfunction Detected (Intermittent/Confirmed)
• P0201 (17355): Injector: Cylinder 1 (N30) – Circuit Malfunction (MIL ON – Intermittent/Confirmed)
• P0301 (15125): Cylinder 1 – Misfire Detected (MIL ON – Confirmed)
• P0303 (15131): Cylinder 3 – Misfire Detected (MIL ON – Confirmed)
• P0304 (15134): Cylinder 4 – Misfire Detected (Not Confirmed – Intermittent)
• P0302 (15128): Cylinder 2 – Misfire Detected (Not Confirmed – Intermittent)
• P0300 (15137): Random/Multiple Cylinder Misfire Detected (MIL ON – Confirmed)

These codes collectively point to misfires across multiple cylinders and specific issues with the injector circuit for cylinder 1, along with a general fuel injector monitoring malfunction. While the new spark plugs and coils are unlikely to be the direct cause of these fuel-related codes, further diagnosis is necessary to pinpoint whether the issue lies with the fuel pump, the injectors themselves, or another component within the fuel delivery system of this 2015 VW GTI.