A 2014 Mercedes-Benz GLA (X156) arrived in the bay with an airbag fault and an engine code that triggered no dashboard warning. The technician pulled codes P06DA00, B275013, and B005013, presenting a mix of powertrain and safety system issues that usually send mechanics down completely separate diagnostic paths.
Tracing the dual SRS codes under the driver seat
The two body codes, B275013 and B005013, both indicated open circuits on the driver side. The first code points to the driver side airbag squib, while the second flags the seat belt buckle sensor. Our diagnostic platform ranked a shared wiring issue as the most likely cause at 85 percent probability.
In the Mercedes-Benz GLA (X156), these components share a common wiring harness and connector beneath the driver seat. Regular seat adjustment back and forth creates tension on the harness over time. This movement often leads to loose contacts, chafed cables, or spread terminal pins inside the yellow SRS connectors. The most direct diagnostic step is to inspect these yellow connectors for damage and verify the continuity from the SRS control unit to the seat connector.
Our data also ranked a failed microswitch inside the seat belt buckle at a 35 percent probability for the B005013 code, caused by normal mechanical wear from daily use. Checking the live buckle status data in the SRS unit helps rule this out before replacing hardware.
The silent engine code P06DA00
The engine fault presented a different challenge. The vehicle logged P06DA00 in the MED40 engine control unit, yet the check engine light remained off. Our platform identified technical service bulletin LI07.70-P-070763 as an 80 percent probability match for this exact condition.
On M270 engines built up to 2018, this code can appear without triggering a dashboard warning or causing drivability issues. The manufacturer specifies that in these cases, the oil pump defaults to a fail-safe mechanical mode with maximum oil pressure. The bulletin notes this can be ignored or resolved with a software update to the ME/MED40 control unit, making XENTRY software verification the primary test.
Ruling out the mechanical oil pump valve
If the software is up to date, the hardware becomes the suspect. Our engine ranked a defective Y130 oil pump valve or its internal wiring at 75 percent probability.
On M270 and M274 engines, the Y130 solenoid and its wiring harness (part number A 274 150 86 02) sit directly inside the oil pan. Constant exposure to hot engine oil degrades the wiring insulation, causing micro-fractures in the copper or an internal open circuit in the solenoid coil itself. Before dropping the oil pan, a technician should measure the resistance across the Y130 valve at the external connector.
Diagnostic takeaways for the X156
When faced with multiple open circuit SRS codes on a single seat, always check the harness connectors for tension damage before suspecting the individual sensors. For the P06DA00 oil pump code on an M270 engine without a check engine light, verify the software calibration against manufacturer bulletins before testing the internal oil pan wiring.
Reference pages for the codes in this article
- B0050: what we measure for this code across real diagnostics
