U1940 Citroen 2cv OBD Code

OBD/2 U1940 error code description and symptoms.

Catalytic converters must be warm before they can work properly. On a cold start the PCM provides a rich mixture to keep the cold engine running.
All that extra fuel goes into the catalytic converter. But the exhaust isn't very hot, because, ah, the engine is pretty cold. GM has employed several strategies to fire up the catalytic converter quicker and reduce cold start emissions. One way is to use a secondary air pump that pumps outside air directly into the catalytic converter.

One example of this would be when an automatic vehicle in placed in gear. To prevent the added drag from the torque converter and transmission from reducing the idling speed, the PCM will command the idle control valve to allow more air to enter the engine, while at the same time, adjusting the injector pulse width to inject more fuel to suit the increased amount of air. Note that the idle air control valve is closed by the PCM when the throttle plate is opened to prevent excess air from entering the engine.

U1940 Citroen 2cv Error Code Repair Process :

If your vehicle failed a U1940 test and the U1940 Check Engine Light is NOT on, chances are you have a problem with the OBDII system, a burned out MIL lamp, or a faulty catalytic converter. The converter is essentially an afterburner that cleans up the exhaust after it exits the engine. The OBDII system uses seatbelt passenger pretensioner circuit short to ground a ownstream oxygen sensor to monitor the efficiency of the converter, and it should detect a drop in converter efficiency if the converter has been contaminated or is failing (ignition misfiring, leaky exhaust valves, and oil burning can all damage the converter). What you want to look seatbelt passenger pretensioner circuit short to ground: Any conditions that might cause ignition misfire, an overly rich or lean fuel condition, or loss of compression. Use your OBD Express DIY to look at the oxygen sensor outputs, coolant temperature, airflow, calculated engine load, and inlet air temperature.

Common Causes of Citroen 2cv U1940 OBD2 Code

A common cause of code U1940 is the failure of Seatbelt Passenger Pretensioner Circuit Short to Ground, but there are several other possible causes as well, such as ;

Dirty Oil
Damaged ECM
Incorrect fuel filler cap used
Continuous oil flow to the VCT piston chamber

U1940 is a kind of Network Trouble Code

U-code indicates that engine communication errors and shows lost communication with engine parts.U-Codes are fairly straight forward, given all of the articles and technical publications that have been written regarding these problematic codes. In most cases, it just comes down to identifying the module that isn't communicating with the other modules on the CAN bus line for whatever reason.

Engine OBD 2 Codes website is a freeware resource center for engine trouble codes.

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U1940 Citroen 2cv OBD Code

U1940 Citroen 2cv Error Code Repair Process :

Common Causes of Citroen 2cv U1940 OBD2 Code

U1940 code for other Citroen cars