P070C DTC Code: Troubleshooting and Diagnosis


The P070C diagnostic trouble code (DTC) is a generic powertrain code that indicates a fault in the transmission control module (TCM) power relay sense circuit. This code typically appears on vehicles equipped with automatic transmissions. When the TCM power relay sense circuit fails, it can result in various transmission-related issues such as harsh shifting, transmission slippage, or even the inability to shift gears.

Understanding the P070C DTC code is crucial as it helps identify the root cause of the transmission problem and guides technicians during troubleshooting and diagnosis. In this article, we will delve deep into the causes, symptoms, and potential solutions for P070C.

Causes of P070C DTC Code

There are several potential causes for the P070C DTC code to trigger. Understanding these causes will help pinpoint the specific issue and allow for effective troubleshooting and repair. Some common triggers for this code include:

  1. Faulty TCM power relay - The TCM power relay is responsible for supplying power to the transmission control module. If the relay becomes faulty, it can interrupt the power supply, leading to a P070C code.

  2. Wiring or connection issues - Loose or corroded wiring connections between the TCM, power relay, or battery can disrupt the power flow and result in the P070C code.

  3. Defective TCM - The transmission control module itself may have internal faults or malfunctions that cause the TCM power relay sense circuit to fail.

Symptoms of P070C DTC Code

When the P070C DTC code is present, it can manifest in various symptoms, depending on the severity of the issue and the vehicle’s make and model. Some common symptoms associated with this code include:

  • Harsh shifting: One of the noticeable signs of a P070C fault is when the transmission exhibits abnormal and rough shifting patterns. This could include delayed shifting, sudden jerks, or excessive RPM fluctuation during gear changes.

  • Transmission slippage: Another symptom is the transmission slipping out of gear unexpectedly while driving. This can lead to a loss of power or an inability to accelerate properly.

  • Inability to shift gears: The vehicle may get stuck in a particular gear and fail to shift up or down as commanded by the driver or the vehicle’s computer.

  • Illuminated Check Engine Light: The P070C DTC code triggers the Check Engine Light (CEL) on the vehicle’s dashboard, signaling a transmission-related issue that requires attention.

It is essential to address these symptoms promptly to prevent further damage to the transmission and maintain the vehicle’s overall performance.

Diagnosis of P070C DTC Code

Diagnosing the P070C DTC code involves a systematic approach to identify the underlying cause. Here is a step-by-step diagnostic process:

Step 1: Scan for codes

Using an OBD-II scanner, retrieve all stored trouble codes from the vehicle’s onboard computer system. Codes related to the transmission or powertrain should be noted for further analysis.

Step 2: Visual inspection

Visually inspect the wiring harnesses, connectors, and components related to the TCM power relay sense circuit. Look for any visible signs of damage, loose connections, or corrosion. Repair or replace any damaged or faulty components as necessary.

Step 3: Test the TCM power relay

With the assistance of a multimeter, check the resistance and continuity of the TCM power relay. Compare the readings to the manufacturer’s specifications. If the relay fails these tests, it should be replaced.

Step 4: Verify power supply

Ensure that the TCM is receiving the proper power supply by testing the input voltage to the TCM. Insufficient voltage can trigger the P070C code. If the voltage is not within specifications, investigate and repair the power supply issue accordingly.

Step 5: TCM functionality

If all the previous steps do not yield a resolution, it may be necessary to test the TCM itself. This can be done using specialized diagnostic tools or by consulting the vehicle’s service manual. Professional assistance may be required at this stage.

Frequently Asked Questions

Q1: Can driving with a P070C code damage the transmission?

A1: It is not recommended to drive with a P070C code because it can lead to transmission-related problems. Continued driving without addressing the issue may cause further damage, resulting in more expensive repairs.

Q2: How much does it cost to fix a P070C DTC code?

A2: The cost to fix a P070C code can vary depending on factors such as the vehicle’s make and model, the severity of the issue, and labor rates in your area. Typically, the cost ranges from $100 to $500 for parts and labor.

Q3: Can I repair a P070C code myself?

A3: While basic inspections and testing may be performed by skilled DIY enthusiasts, it is recommended to seek professional assistance for accurate diagnosis and repair of the P070C code. A qualified technician will have the necessary tools and knowledge to address the issue effectively.


The P070C DTC code can indicate a fault in the transmission control module power relay sense circuit. Understanding the causes, symptoms, and diagnostic process outlined in this article will help you troubleshoot and resolve the issue efficiently. Remember to address the problem promptly to prevent further damage to the transmission and ensure the overall performance and safety of your vehicle.

About author


Meet Sam Mitchell, your experienced and reliable guide in the complex world of car fault codes. With a robust career spanning over 15 years as a professional car mechanic, John has the skills, knowledge, and practical experience to help you navigate car fault issues with confidence.


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