Volvo 850 engine shuts off unexpectedly during drives, issue worsens in summer on Volvo 850

Some Volvo 850 owners report experiencing unexpected engine shutdowns during drives, particularly worsening in the summer months. These shutdowns may be linked to known issues such as problems with the earthing for the ignition amplifier, which can lead to engine failure. Additionally, the ignition switch could contribute to the problem, especially when a heavy load of keys is frequently attached. Intermittent fuel pump relay issues are also reported, which can exacerbate shutdowns in warmer weather. Owners have noted that low or rough idling, as well as high RPMs, may indicate a faulty Mass Airflow Sensor (MAF). To diagnose these issues, some owners suggest checking for visible sparks from the spark plug wires. It is recommended to inspect the ignition system, fuel pump relay, and MAF to effectively troubleshoot and resolve the engine shutdown concerns.