Codes 40, 21, 34 and 13?

The codes you provided appear to be OBD-II diagnostic trouble codes (DTCs). Here's a brief explanation of each code:

Code 40: This code refers to an issue with the Exhaust Gas Recirculation (EGR) system. It typically indicates a problem with the EGR control circuit, such as a malfunctioning EGR valve or a faulty EGR solenoid. A diagnostic inspection of the EGR system is needed to determine the exact cause.

Code 21: This code relates to a problem with the oxygen sensor circuit for the engine's bank 1 sensor 1. The oxygen sensor measures the oxygen content in the exhaust gases and provides feedback to the engine control module (ECM). A malfunctioning oxygen sensor or issues with its wiring can trigger this code.

Code 34: This code refers to a fault in the MAP (Manifold Absolute Pressure) sensor circuit. The MAP sensor measures the intake manifold pressure and provides data to the ECM for engine control. A faulty MAP sensor, wiring issues, or vacuum leaks in the intake manifold could be the potential causes.

Code 13: This code relates to a malfunction in the engine's air intake temperature sensor circuit. The air intake temperature sensor measures the temperature of the incoming air, allowing the ECM to adjust fuel delivery accordingly. A faulty sensor or wiring issues can trigger this code.