C1209 Diagnostic Trouble Code

C1209 is a kind of OBD-II Diagnostic C-Chassis Diagnostic Trouble Code.

It is considered generic because it applies to all makes and models of vehicles, although specific repair steps may be different depending on your car model.

Symptoms

Symptoms of a C1209 diagnostic trouble code may include:

Lack of power
Faulty O2 Sensor
Poor acceleration
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.

Possible Causes :

An air leak forward of the DPF will change the sensor readings resulting in the code
Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
Rough running engine due to misfiring plugs. Many engines have misfire codes to indicate the cylinder effected, such as P0307 for number 7.

Repair Processes :

Look for rubbing, scraping, bare wires, worn spots or melted plastic connectors. Pull the connectors apart and carefully look at the terminals (the metal parts) inside the connectors. With the valve disconnected, the red voltmeter lead should be attached to the IMRC valve power wire and the black voltmeter lead connected to ground. Replace the oxygen sensor that is downstream from the catalytic converter on the side of the engine that does not contain cylinder #1. Also, if a oxygen sensor code stating "heater circuit malfunction" the sensor has most probably failed.

Process Tips

Diagnostic trouble code C1209 is not difficult to diagnose and repair. Thus, it always pays to have a qualified technician to look after your vehicle should this error code arise.

Diagnosing this code requires the engine to be in good running shape, without unmetered air entering the engine. If other codes that relates to misfiring condition, lean running or air entering the engine is present, then you must first fix those error codes before C1209.

Fortunately, C1209 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

C1209 Trouble Code For Specific Cars

C1209 Melkus Rs1000 A/C Request Signal Circuit Short to Ground
C1209 Porsche Cayman Type 981 Fuel Pump Low Speed Malfunction
C1209 Pininfarina Osee EV Battery Pack Temperature Fault
C1209 Smart Forfour Lamp Air Bag Warning Indicator Circuit Failure
C1209 Acura El ABS Hydraulic Pressure Differential Switch Input Short Circuit To Ground
C1209 Opel Rekord Door Ajar RR Circuit Short To Battery
C1209 Toyota Prius 2 Park Brake Actuator Assembly Switch Applied Circuit Short to Gnd