What does it mean?
This diagnostic code (DTC) is a generic powertrain code, meaning it applies to vehicles equipped with OBD-II (Dodge, Ram, Ford, GMC, Chevrolet, VW, Toyota, etc.). Although generic, specific repair steps may vary by make/model.
When I come across a stored P0419 code, I know that the Powertrain Control Module (PCM) has detected a malfunction in a relay circuit of the Secondary Air Injection (SAI) system. The designation B refers to a specific relay in a system that uses multiple relays.
Modern automobiles use SAI systems as a method to reduce harmful exhaust emissions by introducing ambient air into the engine’s exhaust system. SAI designs include a belt-driven pump or an electric pump to draw in ambient air, slightly compress it, and inject the pressurized air into the engine’s exhaust manifolds. The PCM electronically controls one-way valves, switching valves, anti-flame backflow valves, and bypass valves to regulate and distribute air pressure and protect the SAI pump.
Fluctuations in the SAI system pressure are monitored by the PCM using voltage input signals from one or more pressure sensors. When the SAI pressure falls below a certain level, the PCM electronically opens the necessary valves and allows secondary air to be pumped into the exhaust system. Engine temperature, engine speed, and vehicle speed are also considered in activating the SAI pump.
In vehicles equipped with electric pumps, the PCM monitors the SAI pressure sensors and activates the pump if needed. The system relay is used to transfer battery voltage from the fuse panel or fuse link to the SAI pump.
If the PCM detects a voltage input signal from the SAI relay circuit (designated by B) indicating that a malfunction has occurred, a P0419 code will be stored, and a malfunction indicator light may be illuminated.
Other secondary air injection system fault codes include P0410, P0411, P0412, P0413, P0414, P0415, P0416, P0417, P0418, P041F, P044F, P0491, and P0492.
Code Severity and Symptoms
It is not necessary to address a stored P0419 code with great urgency. The SAI system is only associated with reducing exhaust emissions and is not essential to engine operation.
Symptoms of this code may include:
Frequently, no symptoms are displayed with a stored P0419 code
No activation of the SAI pump
Causes
Possible causes for setting this code are as follows:
Faulty SAI pump relay
Short-circuited wiring, components, and/or connectors in the SAI system
Faulty SAI pump
Blown SAI system fuses
Diagnostic and Repair Procedures
To accurately diagnose a P0419 code, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source (such as All Data DIY) will be necessary.
Inspect the system wiring, connectors, and the serpentine belt that drives the pump (if applicable) to begin your diagnosis. Repair or replace burnt, corroded, or damaged circuits as needed and retest the system. Check the system fuses and relays at this point if the SAI pump is driven by an electric motor.
Continue by connecting the scanner to the vehicle’s diagnostic port and retrieving all stored codes and freeze frame data, if your visual inspection indicates no obvious malfunction. You’ll want to note this information as it may be helpful later. Then, clear the codes and test the vehicle to see if the P0419 resets.
Look for Technical Service Bulletin (TSB) entries that match the code(s) and symptom(s) presented by the vehicle in question using your vehicle information source. Data from hundreds of thousands of repairs are used to compile TSBs, and the information they contain can be very helpful in making an accurate diagnosis. In extremely cold weather conditions, belt-driven SAI pumps are prone to seizing due to frozen condensation. To prevent condensation from reaching the SAI pump, a one-way check valve is typically integrated into the air intake hose. These valves are known to fail and allow exhaust condensation to enter the SAI pump. Ice (frozen condensation) causes the SAI pump (belt-driven) to seize or a fuse to blow and melt (electric pump).
You can use the scanner to activate the electric SAI pump. Once the pump is activated, use the DVOM to test for voltage and ground. Suspect a blown fuse or a faulty power relay if no voltage is detected. Use the DVOM to check for an open circuit between the power source and the pump if all fuses and relays are in good condition. Before using the DVOM to check circuit resistance, disconnect all associated controllers.
Using the DVOM, check the resistance and continuity of individual circuits. Repair or replace circuits that appear open or short-circuited.
Additional diagnostic notes:
Blown fuses are usually a reaction to a short circuit and not the source of the malfunction
Frozen pumps can be thawed before use to avoid catastrophic damage to the pump