Understanding Anti-Pollution Fault Causes In Vehicles

Many Peugeot owners have reported seeing an anti-pollution fault message on their dashboard, accompanied by the engine management light. This warning light could be caused by a number of issues, including a faulty pump regulator, a pressure sensor fault, or a clogged fuel filter. Other potential causes include a faulty BSI housing prone to water ingress during rain, incorrect fuel/air mixture, or a head gasket issue. To diagnose the specific cause of the anti-pollution fault message, it is recommended to take the car to a garage for a diagnostic check, which may include a compression check, a head gasket check, and a review of diagnostic data.

Incorrect fuel/air mixture

The anti-pollution fault light in a Peugeot can indicate a problem with the emissions control system. An incorrect fuel/air mixture can be caused by a variety of issues, including:

Faulty Injectors

Clogged or malfunctioning injectors can disrupt the fuel spray pattern, leading to an incorrect fuel-air mixture. This can be caused by contaminated or low-grade fuel, which can also cause increased emissions.

Clogged Fuel Filter

A dirty or clogged fuel filter restricts fuel flow, impacting combustion and emissions, and leading to an incorrect fuel-air mixture.

Low Fuel Pressure

Leaks in the fuel system or a weak fuel pump can cause low fuel pressure, starving the engine of fuel and resulting in incomplete combustion. This can trigger the anti-pollution fault light.

Faulty Oxygen Sensor

The oxygen sensor monitors the oxygen content in the exhaust, and a faulty one can send inaccurate readings to the ECU, leading to an incorrect fuel-air mixture.

Malfunctioning Mass Air Flow (MAF) Sensor

The MAF sensor measures incoming air, and a faulty one can send inaccurate data to the engine computer, leading to an improper fuel mixture.

Faulty Engine Control Unit (ECU)

The ECU, or the "brain" of the engine, controls various functions, and a malfunction can lead to a cascade of issues, including an incorrect fuel-air mixture.

It is important to have the issue diagnosed and repaired by a qualified mechanic to ensure the vehicle is operating efficiently and meeting emission standards.

Low coolant levels

The coolant temperature sensor or gauge malfunctions, causing the dashboard's overheat warning light to stay on constantly. This will also cause the coolant fan to run constantly and may cause engine idling problems. The low coolant level combined with these other symptoms could be pointing to a head gasket issue. Loss of coolant with no visible external leaks is most often due to a head gasket failure. This causes the air/fuel mixture to be wrong, which is detected by the second sensor in the exhaust.

The antipollution light is indicating that the fuel/air mixture is incorrect. The 'stuttery' symptom may also be connected as a misfire or partial misfire can trigger the antipollution light. It is advised to get a diagnostic check to locate the problem.

The issue may become more critical over time. It could be a minor issue that needs to be fixed or a sign of a bigger problem with the car's pollution control system. It is crucial to address the problem promptly to prevent vehicle damage and ensure compliance with pollution regulations.

Faulty pump regulator or pressure sensor

A faulty pump regulator or pressure sensor can cause an anti-pollution fault in your vehicle. This is because the fuel pressure regulator controls the fuel pressure in the fuel rail, and if it is broken, the air-fuel mixture will be disturbed. This can cause the engine not to produce enough power, leading to performance problems such as hard-starting, rough running, stalling, and a lack of power.

A faulty fuel pressure regulator can also cause fuel leakage, which can lead to bad smells and, in some cases, even cause your car to catch fire. Therefore, it is essential to address fuel leaks immediately.

Some other common symptoms of a bad fuel pressure regulator include a misfiring engine and a check engine light on your dashboard. Black smoke coming out of the exhaust pipe can also indicate a faulty regulator.

It is not very common for the fuel pressure regulator to fail. Still, if you suspect that it might be the cause of your anti-pollution fault, you can check it manually or with an OBD2 scanner at any garage or even at home. To check it manually, you can use a fuel pressure gauge connected to the fuel rail and remove the vacuum hose while the engine is idling. If the fuel pressure is within the correct specifications, the fuel pressure regulator is likely functioning correctly.

If you need to replace the fuel pressure regulator, the cost will vary depending on your car model and labour costs. The regulator itself typically costs between $30 and $200, while labour costs can range from $50 to $300. In some cases, you may need to replace the entire fuel pressure rail or even multiple regulators, which can increase the cost.

Fault in the exhaust temperature sensors

An anti-pollution fault can be caused by a fault in the exhaust temperature sensors. The exhaust gas temperature sensor measures the temperature of the exhaust gas and relays this information back to the engine control unit or ECU. The ECU then takes appropriate action, such as lowering the temperature or increasing the quantity of fuel injected into the catalytic converter.

Faults in the exhaust temperature sensors can occur due to changes in temperature, which result in changes in resistance in the sensor. This change in resistance is communicated to the ECU as a voltage. A faulty sensor communicating incorrect voltages can result in poor fuel efficiency because the DPF regeneration takes longer to complete. This can also affect driveability.

A faulty exhaust temperature sensor can also lead to unnecessary regenerations, causing inconvenience to the vehicle owner. For example, a false reading can cause the EGR system to malfunction, without triggering the check engine light, resulting in a failed emissions test.

To diagnose a faulty exhaust gas temperature sensor, the following steps can be taken:

• Conduct an electronic test and read any fault codes using a diagnostic tool.
• Inspect the connectors for signs of corrosion or loose connections.
• Check the wiring for any breaks or damage that could cause a short to the ground.
• Inspect the sensor for any build-up of contaminants and clean it with a clean, dry cloth if necessary.
• Measure the voltage at the sensor's connector with the vehicle ignition turned on and the plug on the sensor disconnected; it should be 5 volts. If not, trace the wire back to the ECU and check the supply there.
• Use a separate IR measurement device to test the sensor and compare the readings to the live data obtained when using a diagnostic tool.

If the exhaust gas temperature sensor is faulty, it needs to be replaced. To replace the sensor, first locate it, noting that the position can vary depending on its function. Next, disconnect the electrical connector and unscrew the sensor using a socket wrench, taking care not to damage nearby components. Install the new sensor and torque tighten it to the vehicle manufacturer's recommendations. Finally, perform a road test to ensure the check engine light is off and the exhaust system is functioning correctly.

Water ingress and accumulation

In the context of an anti-pollution fault in cars, water ingress and accumulation can occur in the BSI housing and on top of the ECU unit, as well as on the cables and connectors leading to the ECU unit. This can happen due to driving in heavy rain, as the BSI housing is prone to water ingress during rain. The problem is exacerbated when water accumulates and is difficult to remove.

To address this issue, it is necessary to disassemble the affected units, clean them, and ensure they are completely dry. This process may need to be repeated multiple times, and the use of a water-repellent spray can also help to prevent future ingress. However, it is important to note that water-repellent sprays may not completely solve the problem.

Additionally, it is crucial to inspect and clean any connections near the ECU or BSI. Before performing any cleaning or maintenance, always detach the battery to avoid any electrical hazards. Moisture or oxidation in these areas can indicate water ingress and potential electrical faults.

To prevent water ingress in general, it is important to regularly maintain and inspect roofs, gutters, windows, and doors for any signs of wear, gaps, or damage. Proper drainage systems and waterproofing measures, such as sealants and coatings, are also crucial to divert water away from structures and prevent water intrusion.

Frequently asked questions