P0135 on Mercedes-Benz GLS: Fix & DLC Location
Factory diagnostic troubleshooting wire for fault code P0135 (O2 Sensor Heater Circuit Malfunction (Bank 1, Sensor 1)) specifically on the Mercedes-Benz GLS (2020–2026, 3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach)).
1. Symptoms of P0135 on Mercedes-Benz GLS
When the Engine Control Module (ECM/PCM) on your Mercedes-Benz GLS (3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach)) logs fault code P0135, drivers commonly observe:
2. Most Likely Causes on Mercedes-Benz GLS
Historical warranty claims and technical repair bulletins for Mercedes-Benz GLS point to the following failure distribution:
3. Step-by-Step DIY Repair Guide for Mercedes-Benz GLS
Locate the under-hood fuse box and test the O2 sensor heater fuse with a multimeter or test light. on the Mercedes-Benz GLS equipped with 3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach).
Unplug the Bank 1 Sensor 1 connector and test resistance between the two heater pins (typically 3 to 15 ohms). on the Mercedes-Benz GLS equipped with 3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach).
Use an O2 sensor socket wrench to remove the old sensor from the exhaust manifold and install an OEM-spec replacement with anti-seize on the threads. on the Mercedes-Benz GLS equipped with 3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach).
Other Common Fault Codes on Mercedes-Benz GLS
Frequently diagnosed powertrain, emissions, and sensor trouble codes logged on the Mercedes-Benz GLS:
4. Mercedes-Benz GLS P0135 FAQs
What causes code P0135 to trigger on a Mercedes-Benz GLS?
On the Mercedes-Benz GLS (3.0L Turbo I6 (GLS 450) / 4.0L Bi-Turbo V8 (GLS 580 / Maybach)), P0135 is most frequently caused by Burnt-out internal heating element in upstream oxygen sensor or Blown O2 sensor heater fuse.
Where is the OBD-II port located on my Mercedes-Benz GLS?
On the Mercedes-Benz GLS, the 16-pin DLC diagnostic connector is located Driver lower knee bolster trim panel. Plug in any standard OBD-II scanner with the ignition in the ON position to read freeze-frame parameters.
Can I safely drive my Mercedes-Benz GLS with code P0135?
Yes, vehicle is safe to drive, but will stay in open-loop mode longer upon startup. Given that P0135 carries a Low to Medium severity rating, we advise avoiding heavy towing or aggressive throttle inputs until sensor readings are verified.