P0403 OBD-II：废气再循环 "A "控制电路 OBD-II故障代码P0403是什么意思？
OBD-II代码P0403被定义为废气再循环电路故障。
EGR（废气再循环）系统用于降低燃烧温度，从而减少氮氧化物的形成。
代码 P0403 表示 PCM 在允许或拒绝真空以打开或关闭 EGR 阀时，没有看到正确的 EGR 真空电磁阀电压读数。
See_also: P2267 OBD II故障代码 P0403 症状
- 发动机检查指示灯点亮
- 在大多数情况下，驾驶员不会注意到任何不利条件
- 在某些情况下，可能会出现性能问题，例如在加速时、发动机处于负荷状态时或在车辆高速行驶时出现 "呯呯 "声。
触发P0403代码的常见问题
EGR真空电磁阀故障
EGR通道受限，通常由积碳引起
EGR阀故障
EGR阀缺乏适当的真空或电信号
EGR系统缺乏对电脑的正确反馈：
See_also: P0826 OBD II故障代码- 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）。
P0403 车间和技术人员诊断理论
PCM通过将EGR真空电磁阀接地来控制流向EGR阀的真空，它通过打开EGR真空电磁阀接地电路来关闭真空供应。 P0403可在正常行驶条件下或进行EGR OBD-II监控器测试时设定。 EGR OBD-II监控器部署了一套测试标准，通常在至少两种不同的行驶条件下运行--稳速行驶和高速行驶。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P0403通常是 不 EGR阀本身的问题，而是EGR真空电磁阀电路告诉PCM，EGR真空电磁阀电路中没有正确的电压。 因此，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P0403，冻结帧数据应该是： - EGR阀本身的问题，而是EGR真空电磁阀电路告诉PCM，EGR真空电磁阀电路中没有正确的电压。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，从而监测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），则很可能是一个或多个EGR通道或气缸堵塞或非常受限，使得EGR只进入一个或两个气缸。 当出现这种情况时，您可能会发现失火，甚至出现与P0400同时出现的失火代码。 这种情况可能发生在使用EGR "流道 "的车辆上。气缸
Ronald Thomas
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