P0406 OBD-II: 废气再循环传感器 "A "电路高 OBD-II故障代码P0406是什么意思？
OBD-II代码P0406定义为废气再循环传感器A电路高电平。
当发动机燃烧温度过高（2500°F）时，就会产生氮氧化物气体，这种气体是导致酸雨和某些人呼吸道疾病的主要原因。
代码 P0406 表示EGR阀位置传感器的电压读数过高，通常高于4.0 - 4.5的电压范围。
P0406 症状
- 发动机检查指示灯点亮
- 在许多情况下，可能会出现性能问题，如加速时、发动机负荷时或高速行驶时的 "呯呯 "声。
- 在某些情况下，驾驶员没有注意到任何不利条件
触发P0406代码的常见问题
EGR阀位置传感器故障
EGR阀位置传感器连接器和/或接线故障
EGR阀有故障并粘住不打开
EGR阀积炭，不能正常关闭
See_also: P0113 OBDII故障代码 EGR阀的真空或电信号不正确
EGR真空供应电磁阀故障
EGR系统对计算机的反馈不正确：
- 歧管绝对压力传感器 (MAP)
- EGR压差反馈传感器（DPFE）
- EGR阀位置传感器（EVP）
- EGR温度传感器
基础知识
废气再循环（EGR）系统回收排气系统中的少量废气（通常不超过10%），并将其与进入燃烧室的进气歧管空气混合。 这种惰性（或不可燃）废气的加入将燃烧峰值温度限制在低于2500°F的范围内，在此范围内会形成氮氧化物（NOx）。在某些情况下，当发动机因EGR流量严重不足而出现 "呯呯 "和/或严重爆震时，可能会发生点火错误，从而导致尾气中释放未完全燃烧的碳氢化合物（HC）。
See_also: P0597 OBD II故障代码 面向修理厂和技术人员的P0406诊断理论
例如，EGR阀位置传感器告诉PCM，EGR阀大开，而EGR阀应该关闭，并且没有支持数据告诉PCM，EGR正在流动。 EGR位置传感器电路故障代码可在正常驾驶条件下或执行EGR OBD-II监控器测试时设置。 EGR OBD-II监控器部署了一组测试有些监测器使用长减速沿稳定速度数据来确定EGR监测器是否正确通过。
发动机控制模块通过多种方式确定适当的EGR流量：
- 当EGR应该流动时，EGR通道内温度升高
- 当EGR应该流动时，可测量的歧管压力变化量
- 前氧传感器信号发生可测量的变化（通常是下降
- EGR阀位置传感器测量的EGR阀位置变化
- 由爆震传感器测量的火花塞爆震量
- 数字式EGR压力反馈传感器测量的排气背压下降量
代码P0406通常是 不 相反，EGR阀位置传感器告诉PCM，没有正确数量的EGR回流到燃烧过程中，以充分冷却点火峰值温度。 一旦用扫描工具检索到代码P0406，应记录和分析冻结帧数据，以确定当时的发动机状况。建议在连接数据流扫描工具的情况下驾驶车辆，以重复代码设置条件，从而可以监控EGR阀位置传感器、执行部件和反馈传感器的行为。
确定问题是EGR控制问题、系统堵塞或受限，还是反馈装置故障的常见测试方法
注意事项
如果EGR阀升起时氮氧化物下降（该测试通常在测功机上进行），则可能是一个或多个EGR通道或气缸被堵塞或受到很大限制，使得EGR只进入一个或两个气缸。 当发生这种情况时，您可能会发现失火，甚至出现与P0404同时出现的失火代码。 这种情况可能发生在每缸使用EGR "流道 "的车辆上。气缸
Ronald Thomas
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