P1666 Diagnostic Trouble Code

P1666 is a kind of OBD-II Diagnostic P-Powertrain 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 P1666 diagnostic trouble code may include:

Misfire
Misfire
The light may stay on or light intermittently as the DPF regenerates. The engine will be sluggish on acceleration.
Reduction in engine performance, especially at low RPM levels

Possible Causes :

Dirty air cleaner element Damaged DPF
A plugged converter will cause of host of driveability problems as well as set this code. A severely plugged converter will result in the inability to increase rpm when under load. Look for a code such as P0421 -- catalytic converter efficiency below threshold if the converter indicating a faulty converter.
An air leak forward of the DPF will change the sensor readings resulting in the code

Repair Processes :

Pack the connector cavity with dielectric silicone compound (same stuff they use for light bulb sockets and spark plug wires) and reassemble. Find out what kind of system you have and verify that voltage to the fuel level sensor is present at the fuel pump wiring harness.

Process Tips

Diagnostic trouble code P1666 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 P1666.

Fortunately, P1666 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P1666 Trouble Code For Specific Cars

P1666 Darracq 8 Heated Catalyst Temperature Below Threshold (Bank 1)
P1666 Abarth Renault A/C Post Heater Sensor Circuit Short To Ground
P1666 Stearns Knight B Lamp Park Input Circuit Short To Battery
P1666 Opel Corsa C Decklid Release Circuit Short To Ground
P1666 Toyota Sports Passenger Door Ajar Circuit Failure
P1666 Csc Mark Iii Fuel Temperature Sensor #1 Circuit Failure
P1666 Land Rover Evoque Steering Phase B Circuit Short To Ground