Error Code P0127: What It Means & What To Do?

<<See All OBD Codes

Inadequate engine heat-up time, a coolant temperature sensor defect, a low engine coolant condition, or a thermostat error could cause this.

ECT sensor readings that happen after the OBD-II system has been sent into closed loop operation, and are lower than the manufacturer’s defined value, will cause a trouble code to be stored and a malfunction indicator lamp to be illuminated.

What causes this problem with the Throttle Position Sensor/Switch A Circuit?

• IAT sensor harness has been left unplugged
• IAT sensor wiring and/or connectors are open or shorted
• Faulty IAT sensor
• Defected MAF sensor
• Jammed air filter
• Broken intake air inlet pipe

1. Boost Pressure Sensor - If the boost pressure sensor is defective, you will notice a loss of boost power and reduction of productivity in your engine. If there is damage to your boost pressure sensor, you should have it replaced to prevent your turbocharged car from losing its expertise.
2. Turbocharger ­- The turbocharger may falter due to lowering oil levels, which means excess heat and abrasion will eventually founder the bearings that are inside. This signals that you need to replace the turbocharger or use internal lubricants to be sure all the parts are performing effectively.
3. Supercharger - A supercharger can start to get faltered for a variety of reasons, such as low levels in supercharger oil, fragmented pulley, and overheating or defected seals/gaskets. If your car's supercharger is not performing correctly, you need to replace it as early as possible.
4. Knock Sensor - When detecting a knock sensor, ensure there are no damaged terminal or no damaged wires and connections. A defective knock sensor decreases your car’s performance, reduces fuel economy and gives your engine costly damage, so it’s critical to get the right knock sensor for your type of car demands.
5. Spark Plug - A faulty spark plug may occur when acceleration is slow, power is at loss, fuel economy is poor, the engine is misfiring and the car has difficulty starting. Likewise, it is highly advised to replace your spark every 30 months or 30,000 miles your car is running.
6. Intake Manifold - A leak found in the intake manifold can pose harmful risks on your car's engine, making the manifold draw in extra air from an outlet through the leak passage, causing extra air to enter intake ports and prevent the air-fuel to correlate in the cylinders. It’s highly recommended to replace the faulty manifold right away to stop any upcoming damage to your car's engine.
7. Boost Pressure Gauge - If the boost pressure sensor is failing, you will notice a reduction of
   boost power and a decrease of efficiency in your engine. If you notice signs of damage to your boost pressure sensor, you should have it replaced to prevent your turbocharged car from losing its efficiency.
8. Powertrain Control Module - A faltering PCM could make your car fail to start or begin stalling while running. Inclusively, poor emissions could occur due to the failure in controlling the emissions system, so if your PCM is not functioning correctly, you should have it replaced instantly.
9. Engine Control Module - Your car might not start even after making sure that its battery and starter are working accurately. If your car's problems narrow down to a defective engine control module, you should have it replaced as soon as possible to prevent more severe risks from harming your car.
10. Wastegate - If too much exhaust gas is passed through the turbine, the unit can over-speed, which puts mechanical stress on it and can cause all sorts of issues, such as breaking shafts, failing compressor wheels, or a surge to the engine's internals and power delivery. It’s feasible to tailor the turbo itself and replace a high-end product with one designed especially for the procedure.

The PCM uses the IAT sensor signal to calculate fuel delivery strategy, thereby a code P0127 has to be appraised as critical. P0127 may have symptoms that include:

Common Symptoms

• Pausing or flowing at idle or on a light speed capacity
• Declining fuel efficiency
• Reduced engine performance (especially on cold start)
• Scanner may also store other drivability codes

The OBD Code P0127 problems can be fixed with some of these common solutions for your particular car engine:

• It makes no difference what car you have; you should check the appropriate Technical Service Bulletins (TSB) as they relate to your car. For such makes as Mazda, there are a few notable TSBs and the repair method is to reprogram the PCM, as a “glitch” will trigger this code in the PCM's programming. That doesn’t mean that if you own a Mazda, this is not possible to repair. There is still a possibility that there is a physical issue with the wiring, thermostat and other components. To restate, it is best to check the TSBs first in advance to replacing components to observe if they are applicable to your vehicle.
• Detect to make sure cooling fan operation is accurate. The fan should be on when turned on, and should be off when turned off. If the cooling fan is constantly on, it could cause the engine to heat up slowly or not heat up to the correct functioning temperature.
• Detect the engine coolant for the temperature level. It the level is low, top up, clear the code and drive the car to observe if it comes back. Allude to the “freeze frame” data and see the live data by using a code scanner to view the value of the engine temperature sensor. Collate with the manufactures proposals.
• Use a laser thermometer to confirm the temperature of the coolant at close and safe range, and measure the temperature of the engine to collate with the value of the sensor reading.
• Examine for a defected thermostat, coolant temperature sensor (CTS) and wiring. Repair as needed.

It’s beneficial to always check for technical service bulletins (TSB) in advance for your specific car. You may have a known issue with your engine that has a known fix easily sought by the manufacturer that can save you time and money during this diagnosis. It is common to use a diagnostic scanner, a digital volt/ohmmeter (DVOM) and a precise car information source (ALL DATA DIY) to diagnose a code P0127.

• To start with, check to ensure that the engine is contained with enough suitable coolant so that the thermostat is performing accurately
• Start your diagnosis by watchfully checking for all wiring and connectors
• View for wiring that is shorted or burned and exchange circuitry and connectors as needed
• Suppose if the system wiring, connectors, and components look to be working in normal order, connect the scanner to the diagnostic connector and record all retained trouble codes and freeze frame data
• This data can be immensely helpful in diagnosing irregular conditions that could have provided to this code being retained
• After clearing the codes, run the car to see if the code comes back
• If the code fails to return instantly, you might have an irregular condition
• Irregular conditions can uphold as being such a challenge to diagnose and in intense cases may need be enabled to worsen before precise diagnosis is able be made. Detect the fan clutch (if equipped)
• This code is often set because the driver does not enable adequate engine heat up time (especially in cold weather)
• It is a good idea to reset the code and see if it comes back when this code is on display.

Common Mistakes When Diagnosing The P0127 Code

• Faulty Engine Thermostat
• Faulty Engine Coolant Temperature Sensor
• Faulty Intake Air Temperature Sensor
• Faulty Cooling System
• Poor Engine Coolant
• Filthy Engine Coolant, leading inaccurate Coolant Temperature Sensor scanning
• Faulty Engine Cooling fan(s) that are always running