AutoCodes – GMC – P1478 GMC

P1478 GMC Code - Particulate Matter Sensor Temperature Circuit High Voltage

Quick Answer

The Particulate Matter (PM) sensor monitors the amount of the particulates (soot) in the diesel exhaust gas exiting the tailpipe. Common causes include Faulty Exhaust Particulate Matter Sensor, Exhaust Particulate Matter Sensor harness is open or shorted, Exhaust Particulate Matter Sensor circuit poor electrical connection. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

What it means: P1478 GMC indicates Particulate Matter Sensor Temperature Circuit High Voltage.
Common causes: Common causes include Faulty Exhaust Particulate Matter Sensor, Exhaust Particulate Matter Sensor harness is open or shorted, Exhaust Particulate Matter Sensor circuit poor electrical connection.
Severity: High - diagnose this code as soon as possible.
Can I drive?: Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.

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Code Popularity 3,517

How popular is this code, among other codes? Low

Repair Importance Level

Urgent (Diagnose now) (3 / 3)

Repair Difficulty Level

Advanced (Pro) (3 / 3)

What is this?

Table of contents Created and updated by William Orellana on Sep 30, 2022

Description
Possible Causes
How To Fix
Cost to Diagnose
FAQs
Comments
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Code P1478 GMC Description

The Particulate Matter (PM) sensor monitors the amount of the particulates (soot) in the diesel exhaust gas exiting the tailpipe. The PM sensor is similar to the heated oxygen sensor with a ceramic element but also includes an individually calibrated Sensor Control Unit (SCU). The sensing element includes comb-shaped Interdigital Electrodes (IDE), a heater and a positive temperature coefficient resistor for temperature measurement.
The operation of the PM Sensor is based on the electrical conductivity characteristic of the diesel particulate. As the exhaust gas flows over the sensing element, soot is absorbed in the combs between the electrodes, eventually creating a conductive path. When the path is formed, it generates a current based on the voltage being applied to the element. The measurement process continues until a preset current value is reached. To avoid misleading readings, the sensor performs a regeneration where the soot is cleaned off by heating up the element before the measurement phase begins. The amount of regenerations is based on vehicle strategy; when the calibrated number of regenerations is reached, the cumulative current readings are used to determine the amount of soot concentration in the exhaust gas which in turn determines the collection efficiency of the Diesel Particulate Filter (DPF).
The Diagnostic Trouble Code (DTC) will be set when the particular matter sensor control unit detects a fault in the particulate matter sensor circuitry.

OBDII Code P1478 GMC - Particulate Matter Sensor Temperature Circuit High Voltage - AutoCodes.com — P1478 GMC Code - Particulate Matter Sensor Temperature Circuit High Voltage

What does this mean?

What are the Possible Causes of the DTC P1478 GMC?

Faulty Exhaust Particulate Matter Sensor
Exhaust Particulate Matter Sensor harness is open or shorted
Exhaust Particulate Matter Sensor circuit poor electrical connection

How to Fix the DTC P1478 GMC?

Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.

What is the Cost to Diagnose the Code?

Labor: 1.0

To diagnose the P1478 GMC code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.

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Need Help with the Code?

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Information for Specific GMC Models

P1478 2014 GMC Sierra — Particulate Matter Sensor Temperature Circuit High Voltage
P1478 2015 GMC Sierra — Particulate Matter Sensor Temperature Circuit High Voltage
P1478 2016 GMC Sierra — Particulate Matter Sensor Temperature Circuit High Voltage
P1478 2017 GMC Sierra — Particulate Matter Sensor Temperature Circuit High Voltage
P1478 2018 GMC Sierra — Particulate Matter Sensor Temperature Circuit High Voltage

About the author: William Orellana is a Master Mechanic and Mechanical Engineer with over 30 years of experience diagnosing and repairing vehicles. Learn more about his background.

Frequently Asked Questions about P1478 GMC Code

1. What are common symptoms of OBDII code P1478 GMC related to the Particulate Matter Sensor Temperature Circuit High Voltage?

Symptoms may include reduced engine performance, decreased fuel efficiency, and the illumination of the Check Engine Light.

2. What are possible causes of OBDII code P1478 GMC?

Potential causes include a faulty particulate matter sensor, damaged wiring or connectors in the sensor circuit, or issues with the engine control module (ECM).

3. How can I diagnose the Particulate Matter Sensor Temperature Circuit High Voltage issue?

Diagnosis typically involves using an OBDII scanner to retrieve the specific fault code, inspecting the sensor and its wiring for damage, and testing the sensor's resistance and voltage values.

4. Can I drive my vehicle with OBDII code P1478 GMC active?

It is generally not recommended to drive with this code active, as it can lead to further damage to the engine and emissions system. It is advisable to address the issue promptly.

5. How can I repair OBDII code P1478 GMC?

Repair may involve replacing the particulate matter sensor, repairing or replacing damaged wiring or connectors, or reprogramming the engine control module (ECM) if necessary.

6. Are there any DIY tips for fixing the Particulate Matter Sensor Temperature Circuit High Voltage problem?

While some basic troubleshooting like checking for loose connections or damaged wires can be done by DIY enthusiasts, complex repairs or sensor replacements are best left to professional mechanics.

7. Will resetting the OBDII code P1478 GMC clear the issue?

Simply clearing the code without addressing the underlying problem will not resolve the issue permanently. It is crucial to diagnose and repair the root cause of the fault code.

8. Can extreme weather conditions trigger OBDII code P1478 GMC?

Extreme temperatures or environmental conditions can sometimes affect sensor performance, potentially leading to the Particulate Matter Sensor Temperature Circuit High Voltage fault.

9. How long does it typically take to repair OBDII code P1478 GMC?

The repair time can vary depending on the exact cause of the issue and the complexity of the repair. It is advisable to consult a professional mechanic for a more accurate estimate.

10. Is OBDII code P1478 GMC a serious problem?

While the severity of the issue can vary, it is important to address any fault codes promptly to prevent potential damage to the vehicle's emissions system and ensure optimal engine performance.