P0186 Diagnostic Trouble Code

P0186 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 P0186 diagnostic trouble code may include:

Poor fuel economy
Possible spark knock (detonation / pre-ignition)
Misfire
Engine surge

Possible Causes :

Rusty exhaust systems, cracked exhaust manifolds or damaged or missing gaskets or donuts will cause air leaks.
An air leak forward of the DPF will change the sensor readings resulting in the code
A large vacuum leak would cause a massive amount of un-metered air to enter the intake manifold resulting in an overly lean mixture.

Repair Processes :

If the engine displays a miss and there wasn't a code, determine which cylinder is misfiring. If the exhaust manifold is visible, spay or pour a small amount of water on each cylinder exhaust port. Water will evaporate immediately on good cylinders and slowly on the missing cylinder. If this can't be accomplished pull the plugs and check the condition. Check to make sure they are not burnt or corroded. If in doubt, get some Electrical Contact cleaner at any parts store if cleaning of the terminals is needed. 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 P0186 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 P0186.

Fortunately, P0186 is a fairly common OBD code, meaning that it applies to all makes and models of vehicles made after 1996.

P0186 Trouble Code For Specific Cars

P0186 Reliant Se6 Gate Select Position Circuit High
P0186 Rochet-schneider 30 Hydraulic Pressure Sensor Circuit Low Input
P0186 Studebaker Commander Lamp Turn Signal Rear Output Circuit Short To Battery
P0186 Honda Prelude Rear Echo Sensor Circuit Failure
P0186 Saturn Astra Illuminated Entry Relay Short To Ground
P0186 Daihatsu Mira Generator Lamp "L" Control Circuit Malfunction
P0186 Austin Princess Aux A/C Blower Speed 2 Circuit Failure