P0AC4 Code Fix

P0AC4 Code Fix: Hybrid PCM Requested MIL Illumination

Meaning: Hybrid PCM Requested MIL Illumination
Mostly Seen On: Audi, Chrysler, Nissan, Ford, Isuzu, Subaru
Symptoms: Service Engine Soon Warning Light, Decreased engine power, Poor acceleration, poor fuel efficiency
Reasons: Faulty fuel injector, Damaged Wiring, Faulty ECM, Clogged Fuel Filter, Low fuel Pressure
Affected parts:  HPCM, ECM, MIL, Damaged Fuel Filter, Fuel Injector
Seriousness: Medium
DIY Repair: No
Required Time: Take more than one hour
Related Trouble Codes: P0AC5, P0AC6, P0AC7, P0AC8, P0AC9, P0ACB, P0ACC, P0ACE

An OBD-II code called P0AC4 indicates that the fuel injector circuit of the car is malfunctioning. The code is unique to General Motors cars, and you’ll frequently find it on vehicles like the Chevrolet Silverado, Nissan Altima, Chevy Tahoe Hybrid, GMC Sierra, and Cadillac Escalade. In order to prevent additional harm to your car, you should fix this error code as soon as you can.

Meaning: What is P0AC4 Code?

That is an odd code that causes many problems. The Engine Control Module (ECM) of the car contains a diagnostic problem code called P0AC4. The ECM sets the code when it notices an issue with one or more cylinders’ fuel injector circuits. A number of problems, such as a bad injector, a frayed wire harness, or a broken ECM, might bring this on.Causes of P0AC4 DTC

Causes of P0AC4 DTC

There are several possible causes of a P0AC4 code, including a Faulty fuel injector, Damaged wiring or connector in the fuel injector circuit, Failed ECM, and Low fuel pressure and Clogged fuel filter.  

Faulty fuel injector:

A faulty fuel injector could set off the P0AC4 error code. An engine’s fuel mixture imbalance may result from a malfunctioning injector. Following that, they could make a visual examination of the fuel injector wire and connections to check for any indications of corrosion or damage. The resistance of the fuel injector circuit may be tested with a multimeter to see if there are any visible problems before deciding whether a wiring issue exists.Faulty fuel injector

Damaged wiring or connector in the fuel injector circuit:

The fuel injector circuit’s fuel injector wire damage or corroded connection might also set off the P0AC4 code. The fuel injector circuit may have problems as a result of a weak or erratic connection caused by a broken wire or connector. The mechanic may carry out a fuel pressure test to check the fuel system’s functionality if the wiring and connectors are found to be in excellent shape.connector in the fuel injector circuit

Failed ECM:

The P0AC4 code may be set off as a result of an issue with the Engine Control Module (ECM). The ECM controls the fuel injector circuit, and thus, if it isn’t working correctly, there can be problems with the fuel injector.Failed ECM

Low fuel pressure:

The P0AC4 error code may be set off by low fuel pressure. The fuel injector circuit may have problems if the fuel pressure is not high enough. The fuel injector circuit may have problems setting off the code. If the fuel pressure is low, they could look for damage or blockage in the fuel pump and filter.Low fuel pressure

Clogged fuel filter:

Another factor that might set off the P0AC4 error code is a blocked fuel filter. Fuel injector circuit problems may result from a blocked fuel filter, which restricts fuel flow to the fuel injector. Damaged fuel pump pollution of the fuel electrical connections with wear or damage. Understanding the P0AC4 Code A mechanic will frequently begin by reading the P0AC4 code and any other stored codes in the ECM using a scan tool before diagnosing.Clogged fuel filter

Common Symptoms

According to how serious the problem is, a P0AC4 code’s symptoms might change. Check the Engine Light (CEL) on, reduce engine power, and other symptoms are typical. Misfiring the engine, lackluster acceleration, and a rough idle cause severe damage to the main engine. Low fuel economy is one of the main symptoms. Thus it’s crucial to get your car checked by a skilled technician to find the root of the issue.

  • The most frequent indication that a P0AC4 error has occurred is the Check Engine Light (CEL) turning on. A dashboard warning light called the CEL shows a problem with the engine.
  • Decreased engine power: The engine’s power may be lowered if the P0AC4 code is activated. Because of this, it could be challenging to maintain or increase speed when driving. Engine misfire: An additional P0AC4 code symptom is an engine misfire.
  • The engine may run rough or misfire if the fuel injector is malfunctioning. Another indication that the P0AC4 coding is present is poor acceleration. The engine may struggle to accelerate if the fuel injector isn’t operating correctly.
  • Rough idle: An engine might have a rough idle if the fuel injector is not operating properly. While the engine is idle, this may cause it to feel unsteady or wobbly. An additional sign of the P0AC4 code is poor fuel efficiency.
  • It might result in the engine using more fuel than necessary and poor fuel efficiency if the fuel injector is not operating properly.

P0AC4 Code Fix

The particular resolution for a P0AC4 code depends on what caused it in the first place. In certain circumstances, fixing a broken wire harness or replacing a defective fuel injector may be sufficient to fix the issue. In other circumstances, more involved fixes may be required, such as replacing the ECM or fuel pump. You need to identify the issue’s root if your car has a P0AC4 code. It’s crucial to get it diagnosed by a licensed mechanic. Ignoring the problem might harm your car and cost you more money to fix. Let us have these fixing tips in some step-by-step manner, 

Step 1: Check the Freeze Frame Data

The DTC freeze frame data must first be examined using a diagnostic scan tool to fix the P0AC4 error code. By doing so, you can learn more about the circumstances that led to the code, including the engine’s temperature, the position of the throttle, and the car’s speed. This knowledge can be useful by reducing the number of potential causes of the code.

Step 2: Examine the injector for fuel

The fuel injector will next be checked for wear or damage in the following phase. A malfunctioning fuel injector may set off the P0AC4 code. Replace the fuel injector if it is discovered to be defective.

Next, check for any damage, corrosion, or looseness in the fuel injector circuit’s wire and connector. A corroded or broken connection may activate the P0AC4 code. The wire or connector should be checked for damage and repaired or replaced if necessary.

Step 4: Check ECM

The ECM will next be examined to see if the fuel injector, wiring, and connector are in good working order. A malfunctioning ECM may activate the P0AC4 code. It should be examined using a diagnostic scan tool. If the ECM is discovered to be defective, it should be changed.

Step 5: Replace the faulty fuel filter

Examine the fuel filter and pressure in the fuel system. Secondly, look for any problems with the fuel pressure and fuel filter. The P0AC4 code may be set up by low fuel pressure or a blocked fuel filter. A fuel pressure gauge should be used to check the fuel pressure.

Step 6: Reset the DTC

Use a diagnostic scan tool to erase the DTC. By doing so, the Check Engine Light (CEL) will be extinguished, and the vehicle’s functionality will be confirmed.

What is the Repairing Cost of the DTC P0AC4? 

Depending on the root cause and the location of the problem, the cost of fixing the P0AC4 error might change. The model of the car, replacing parts for a problem with the fuel filter or injector, might cost anywhere from $50 to $300. The price of labor can change based on the mechanic’s hourly rate and the length of time needed to finish the repair, but it normally costs between $100 and $300.

A replacement ECM might cost anywhere between $500 and $1000. In addition, labor expenses might change based on the mechanic’s hourly rate and the length of time required to perform the repair, although they normally fall between $100 and $300. It’s crucial to remember that these are only approximations, and the real cost of fixing the P0AC4 code might change based on a number of variables. You must obtain a more precise estimate of the cost of fixing this code for your particular vehicle, and it is advised that you request a quotation from a licensed mechanic.


An issue with the fuel injector circuit in a General Motors vehicle is indicated by the diagnostic trouble code P0AC4, which is the conclusion. identify the root of the problem if you receive this code; it’s critical to have your car diagnosed by a licensed mechanic. Your car might suffer more damage if the issue is ignored, raising the expense of repairs.

The fuel injector circuit of a General Motors vehicle may be experiencing issues if the P0AC4 diagnostic trouble code is present. The Check Engine Light (CEL) going on, reduced engine power, engine misfire, poor acceleration, rough idle, and poor fuel efficiency are all symptoms of the P0AC4 code. A malfunctioning fuel injector, frayed wire or connector in the fuel injector circuit, an inoperable ECM, low fuel pressure, a clogged fuel filter, or contaminated gasoline are some of the potential reasons for the P0AC4 code. Go through the whole article if you want to diminish this code without any difficulty.

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