Codes This Page Will Cover
- P0405 Exhaust Gas Recirculation Sensor “A” Circuit Low
- P0406 Exhaust Gas Recirculation Sensor “A” Circuit High
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What Is the P0405 Code?
Symptoms
Causes
Seriousness
Can I Still Drive?
Diagnose
Difficulty of Inspecting
Get Additional Help
The P0405 code relates to your engine’s exhaust gas recirculation (EGR) system and the accompanying sensor. The EGR system exists to maintain nitrogen oxide (NOx) emission levels to an acceptable emission level. The EGR sensor that keeps track of the EGR valve works by sending signals to the Powertrain Control Module (PCM). Once the PCM detects a lower than normal voltage level, it triggers the P0405 code.
The PCM uses the EGR position sensor signals to control and adjust the operation of the EGR valve. The EGR system itself dictates how exactly the exhaust gas is routed, and will direct these gasses back into the combustion chamber. The exhaust gas by itself is inert so it is used to displace some of the fuel/air mixture so that the combustion temperatures are regular, sometimes creating excess Nitrogen Oxide. The EGR also manages the flow of that exhaust gas into the engine’s intake manifold that comes from the exhaust manifold. It carries out this operation through a pintle that gets its direction from the PCM. During this process, the PCM will also take in signals from the throttle position (TP) sensor and the engine coolant temperature (ECT) sensor. It will also use readings provided by the manifold absolute pressure (MAP) sensor to determine the pintle’s position. If the PCM receives a signal from the EGR position sensor that is lower than what it deems acceptable during this process, then it triggers the P0405 code. The PCM will trigger the P0406 code if the opposite happens; the EGR position sensor signals a higher voltage reading than expected.
What Are the Symptoms of a P0405 Code?
The first symptom to expect from the P0405 code is the PCM triggering the Check Engine Light on your dashboard. The PCM may also open up the EGR valve more so than usual if the voltage reading is too low, which causes your engine to stall out. This will also cause your engine to hesitate during acceleration because it’s operating on an insufficient air and fuel ratio. The EGR system may also cause your car to run rough and erratic idle. It’s also possible for your engine to start emitting increased levels of NOx and can even cause you to fail emissions tests. During this issue, you may also notice a decrease in engine performance and a decrease in fuel economy.
What Are Some Causes of a P0405 Code?
The first cause to consider when examining the P0405 code issue is a defective EGR valve position sensor. You may also be dealing with a damaged or defective EGR valve or circuit issues leading to the EGR sensor. Damaged or corroded wires can also cause the P0405 problem, and grounded, or shorted wires will trigger the same issue. The return wiring to the EGR sensor can also cause the issue and needs addressing.
How Serious Is the P0405 Code?
The P0405 issue can become severe if left untreated for prolonged periods. The PCM may disable the EGR system altogether, which would affect how your car operates, and you may experience a rough ride. This is why the EGR system needs attention to ensure that it’s working as it should. You shouldn’t risk leaving the issue unaddressed because you can cause further damage to your intake system and engine internals. Instead, you should take your car to a certified service center to have a qualified technician examine it.
Can I Still Drive with a P0405 Code?
You can still drive with a P0405 code, but you’ll be placing more stress and strain on your engine since it’s not operating in ideal running conditions. The EGR system is vital in the smooth operation of your engine, and you shouldn’t jeopardize the health of your engine by continuing to drive it in rough conditions. If you start to hear a pinging from your engine, then you should immediately take your car to a qualified technician to inspect it.
How Easy Is It to Diagnose a P0405 Code?
A technician will begin the diagnostic process of the P0405 code by scanning the stored codes and any available freeze frame data from the PCM. They will then look to clear the codes and perform a road test to see if the codes reappear. Next, they will use the freeze frame data to try and assess the conditions present in the engine when the PCM triggered the P0405 code. The technician will then evaluate the EGR sensor on the scanner to discern if the sensor indicates that the EGR valve is in the proper position. They will also test to see if the EGR sensor is reading a low voltage before inspecting the physical condition of the sensor. The technician will also connect the signal return pin and the reference voltage sensor and examine those readings. Finally, they will physically inspect the wiring and connectors leading to the EGR sensor.
How Difficult Is It to Inspect a P0405 Code?
The inspection process for the P0405 code will begin by assessing the condition of the EGR valve and the EGR position sensor. If either of those parts is defective or damaged, then they will need replacing. A technician is best suited for this process because it takes a lot of attention and testing. They don’t recommend that you DIY this at home because you can easily misdiagnose the root cause of the issue and end up causing more damage to your engine. A technician will also inspect and monitor the voltage coming out of the EGR system and repair any existing vacuum leaks. Finally, they will visually inspect and repair any damaged or corroded wiring in the EGR system and ensure that all connections are firm and secure.
Need Additional Help with Your P0405 Code?
The EGR system is a complicated one, but it’s vital to the healthy operation of your car. You don’t want to risk damage to your engine by ignoring the P0405 issue. Instead, take the correct steps laid out in this guideline, and have it inspected in time to keep your repair bills low.
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