P0108 OBD-II: Manifold Absolute Pressure/Barometric Pressure Circuit High OBD-II故障代码P0108是什么意思？
OBD-II代码P0108定义为歧管绝对压力传感器/大气压力电路高输入。
歧管绝对压力传感器/气压传感器测量进气歧管内空气压力的上升和下降，为动力总成控制模块（PCM）提供控制空燃比、点火正时和排放控制系统许多组件所需的关键数据。
当节气门位置传感器、转速传感器和氧传感器的值发生变化时，MAP/Baro传感器电路提供给PCM的电压持续10秒钟或更长时间高于4.5伏，则代码P0108设定。
See_also: P0692 OBD II故障代码 有此故障代码的车辆应送至修理厂进行诊断。 查找修理厂
P0108 症状
- 发动机检查指示灯点亮
- 在某些情况下，发动机可能难以启动和/或燃油经济性差
- 在某些情况下，发动机性能可能会明显下降
引发P0108代码的常见问题
- 歧管绝对压力传感器/气压传感器故障
- 进气歧管真空泄漏
- 歧管绝对压力传感器/气压传感器接线或连接故障或腐蚀
常见误诊
- 当真正原因是进气歧管真空泄漏时，更换歧管绝对压力传感器/气压传感器
- 当真正原因是EGR阀卡死时，更换歧管绝对压力传感器/气压传感器。
- 当真正的问题是怠速空气控制电动机故障时，更换歧管绝对压力传感器/气压传感器，该故障会导致发动机怠速过低。
排放的污染气体
- HCs（碳氢化合物）：未燃烧的原燃料液滴，有异味，影响呼吸，导致烟雾。
- CO（一氧化碳）：部分燃烧的燃料，是一种无味的致命有毒气体。
- NOX（氮氧化物）：在阳光照射下导致烟雾的两种成分之一。
面向修理厂和技术人员的P0108诊断理论
当诊断 P0108 代码时，重要的是记录冻结帧信息，然后通过试车重复代码设置条件，同时密切注意数据流扫描工具上的发动机负荷、节气门位置、转速和路速。 当您驾驶车辆时，将这些值与 MAP 传感器 PID 或参数 ID 进行比较。 MAP 传感器电压值应上升和下降。通常情况下，该值在加速时为4伏或更高，在减速时为1伏或更低。
See_also: P051B OBD II故障代码 在钥匙打开而发动机关闭的情况下检查MAP传感器连接器。 需要有稳定的5伏参考电压和良好的接地。 第三根导线将是MAP传感器信号线，它将数据发送到动力传动控制模块。 查找并使用正确的发动机性能接线图来辨别这些导线在连接器中的正确颜色和位置。
对MAP传感器进行钥匙开启发动机关闭真空泵电压输出测试是很有帮助的。 您应观察扫描工具上的输出，因为这也将验证线束和连接。 当您施加18-20英寸真空时，电压应从5伏稳步下降到1伏以下。 我还喜欢在施加真空时晃动MAP传感器线束，以确保MAP传感器的电压输出。始终检查MAP传感器的真空软管，如果MAP传感器直接插入进气歧管，请务必检查其密封性，因为它们可能破裂并导致读数不稳定。
Ronald Thomas
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