P0400 indicates an EGR Flow Malfunction. The ECU has detected that the Exhaust Gas Recirculation system is not flowing the expected amount of exhaust gas back into the intake. On the Z32, this is frequently caused by carbon clogging the EGR tubes (especially the one running under the plenum), a failed BPT valve, or a stuck EGR valve itself. It can also be a vacuum leak in the lines controlling the EGR.
P0136 refers to the Oxygen Sensor Circuit Malfunction for Bank 1 Sensor 2. Bank 1 is the right side of the engine (passenger side on US LHD models, driver side on RHD), and Sensor 2 is the rear sensor located after the catalytic converter. This code usually means the sensor itself has failed, the wiring to it is damaged (burned on exhaust is common), or the connector is corroded. Since it is the rear sensor, it monitors catalyst efficiency rather than air-fuel ratio, so it likely won't affect drivability as much as a front sensor would.
P1150 and P1155 are manufacturer-specific codes for the 1996 Twin Turbo. These refer to the Wastegate Valve Control Solenoid Valves. Since you have a Twin Turbo, you have solenoids that manage the wastegate actuators to control boost pressure. P1150 typically points to the wastegate solenoid valve circuit, and P1155 is often listed for the same system (possibly distinguishing between the two solenoids or a specific electrical fault within them). Seeing both simultaneously suggests a potential electrical issue common to both solenoids, such as a shared power supply fuse, a ground issue, or a disconnected harness in the engine bay near the boost control solenoids.
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Dazsw ·
