Code Definition

P1906 — Charge air cooler pump relay circuit open or shorted to ground

System: Powertrain  |  Type: Manufacturer-Specific  |  Make: Audi

About P1906

P1906 is a manufacturer-specific powertrain diagnostic trouble code recorded for Audi vehicles. It belongs to the P-prefix family of codes, which covers engine, transmission, emissions, or fuel-system faults.

When P1906 is stored, the module has detected an open (broken or disconnected) electrical path in the monitored circuit; and a short-circuit (voltage pulled to ground or to supply) in the monitored circuit.

Scanning & clearing: A generic OBD-II scan tool will usually read and clear powertrain (P) codes. For live data, freeze-frame capture, and bi-directional tests you may need a more capable scan tool that supports the vehicle's ECM protocol.

P1906 is a manufacturer-specific code. The same code string on a different make may have a different meaning. Always confirm the code's definition against the vehicle's service information for the specific make and model under test.

Code Information

DTC P1906 sets when the engine control module (ECM) detects an open circuit or a short to ground in the charge air cooler pump relay circuit. On turbocharged and supercharged Audi engines with a liquid cooled intercooler, this electric pump circulates coolant through the charge air cooler to remove heat from the compressed intake air, and the ECM switches it through a relay. When the control circuit is open or shorted to ground, the ECM cannot drive the pump relay, so the pump may not run when needed. Intake air temperatures then climb under boost, and because the ECM retards timing to protect...

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