Code P0103 (Symptoms, Causes and How)

Today’s vehicles are much more efficient than the vehicles of yesteryear. However, this did not happen by accident. The increasingly stringent emissions standards of the 1970s required more revisions and revisions to the design of vehicle powertrains, which eventually led to the introduction of onboard diagnostics.

Today, any late-model vehicle is equipped with numerous computer modules, designed to send and receive various signals. These signals are routed through a complex network of circuits and their corresponding sensors. When everything works as expected, the data delivered by these sensors is interpreted and taken into account by the vehicle’s operating software to improve combustion efficiency.

Sometimes, however, this flow of information does not happen as expected, when there is some kind of obstacle in the way. Such an example is predicted by the P0103 diagnostic trouble code, which indicates a fault in the mass air flow circuit. This code can cause a number of additional problems and symptoms and is often the source of a vehicle’s check engine light.

Read on to learn more about the P0103 diagnostic trouble code, as well as how to resolve these issues should they arise in the future.

What does the P0103 code mean?

The P0103 diagnostic trouble code indicates a problem in the engine mass flow circuit. Specifically, the vehicle’s PCM/ECM has determined that the reflected voltage of this circuit exceeds the expected voltage. However, to fully understand the severity of DTC P0103, you must first know the function of the engine’s MAF sensor.

A vehicle’s MAF sensor is located in the engine intake duct, usually downstream of the air filter housing. This sensor samples each incoming airflow, optimizing the airflow volume as a whole. This information is then transmitted to the vehicle’s operating software.

The feedback provided by a vehicle’s MAF sensor is used to formulate a series of critical equations, including those that determine the engine’s relative fuel settings. Without such feedback, combustion efficiency suffers.

For DTC P0103, the engine PCM/ECM has determined that the feedback provided by the MAF sensor is biased toward the upper part of the expected range, which is considered unreasonable. Simply put, the engine operating software has determined that this data is outside the limits of what is logical in nature.

Related: Code P0101, Code P0102

Code P0103 Symptoms

The P0103 diagnostic trouble code is usually accompanied by several additional symptoms, some of which tend to be more severe than others. Recognizing each of these symptoms can be helpful when trying to diagnose and treat the problem at hand.

These are some of the most common symptoms associated with DTC P0103.

Causes of Code P0103

The P0103 diagnostic trouble code can be caused by many underlying problems, each unique in nature. Understanding these possible causes is often somewhere between getting the vehicle back on the road in a hurry and complete confusion.

These are some of the most common causes of DTC P0103.

Is code P0103 serious?

Generally, a P0103 diagnostic trouble code is considered quite serious. This is because the P0103 code is accompanied by some pretty impressive driving symptoms.

These symptoms include engine stalling problems and starting difficulties. This creates a very real possibility of getting stuck along the way.

Additionally, any vehicle affected by a P0103 diagnostic trouble code is unlikely to pass an emissions test, in any state where such a test is required by the government. This, in itself, can create its own share of difficulties for any motorist.

In any case, the root cause of the P0103 diagnostic trouble code should be diagnosed and corrected as soon as possible. This avoids any additional complications and greatly reduces the risk of being blocked without additional resources.

How to fix code P0103

The following steps can be used to diagnose and repair the root cause of your vehicle’s P0103 trouble code. As always, be sure to consult the factory service documentation specific to your particular vehicle before performing such repairs.

#1: Check for additional DTCs

Before starting the diagnostic process, check for additional diagnostic error codes. All of these codes must be thoroughly diagnosed before proceeding.

#2 – Carefully Inspect the MAF Wiring

Start by carefully inspecting your vehicle’s MAF circuit wiring. Check for signs of pinched, broken or damaged cables. Also, evaluate the condition of all the connectors on the circuit. Repair any damage before continuing.

#3 – Inspect the vacuum system

Next, evaluate your vehicle’s vacuum system for any apparent leaks. Check carefully for inlet leaks or dry, cracked or missing vacuum lines. Any such defect must be rectified immediately.

#4 – Clean the MAF Sensor

You will now clean your vehicle’s MAF sensor using approved cleaning solutions and a soft nylon brush or similar cloth. Be sure to completely remove all dirt from the oil.

#5 – Evaluate O2 Sensor/Baro Sensor Data

Many vehicles use the data provided by all onboard oxygen sensors and barometric pressure sensors to optimize MAF sensor feedback. When using an automotive scan tool, ensure that all data presented by these sensors is within the range specified by the vehicle manufacturer.

#6 – Check voltage/ground/MAF signal

You will now check all input voltages and ground supplies according to the manufacturer’s specific service manual. If the correct voltage and ground values ​​are not present at the MAF sensor, troubleshoot the affected circuit as necessary.

If the supply voltage and ground are within the specified range, but the output readings are still high when the sensor is checked, the MAF sensor will need to be replaced.