P1478 2018 GMC Sierra 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 2018 GMC Sierra 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.
Code P1478 2018 GMC Sierra Description
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.
What are the Possible Causes of the DTC P1478 2018 GMC Sierra?
- 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 2018 GMC Sierra?
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 2018 GMC Sierra 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.
Need more information about the P1478 2018 GMC Sierra code?
Need more information on how to fix the P1478 2018 GMC Sierra code? Get Access to Factory Service Manuals
Need Help with the Code?
Get the P1478 2018 GMC Sierra code diagnosed by a professional: Find a repair shop in your area
Frequently Asked Questions about P1478 2018 GMC Sierra Code
1. What does the OBDII code P1478 mean on a 2018 GMC Sierra?
P1478 indicates a high voltage issue in the Particulate Matter Sensor Temperature Circuit, which monitors exhaust temperature for proper emissions control.
2. What are the symptoms of code P1478 on a 2018 GMC Sierra?
Symptoms may include an illuminated check engine light, decreased fuel efficiency, potential limp mode activation, and increased emissions.
3. What causes the P1478 code on a 2018 GMC Sierra?
Common causes include a faulty particulate matter sensor, damaged wiring or connectors, or an issue with the engine control module (ECM).
4. Can I drive with the P1478 code on my 2018 GMC Sierra?
Driving is possible but not recommended, as it may lead to increased emissions, reduced fuel efficiency, or damage to the emissions system.
5. How is the P1478 code diagnosed on a 2018 GMC Sierra?
Diagnosis typically involves using an OBDII scanner, inspecting the particulate matter sensor and its wiring, and testing the voltage in the temperature circuit.
6. How do I fix the P1478 code on my 2018 GMC Sierra?
Repairs may include replacing the particulate matter sensor, repairing damaged wiring or connectors, or reprogramming the ECM if necessary.
7. How much does it cost to fix the P1478 code on a 2018 GMC Sierra?
Repair costs can vary, but replacing a particulate matter sensor typically ranges from $200 to $500, depending on labor rates and parts pricing.
8. Can a bad particulate matter sensor cause the P1478 code?
Yes, a faulty particulate matter sensor is one of the most common causes of this code.
9. Does the P1478 code affect emissions testing on a 2018 GMC Sierra?
Yes, the code can cause your vehicle to fail emissions testing due to improper monitoring of exhaust particulates.
10. How can I prevent the P1478 code from reoccurring on my 2018 GMC Sierra?
Regularly inspect and maintain the exhaust system, ensure wiring and connectors are in good condition, and address any exhaust-related issues promptly.
Discuss the causes and fixes for P1478 2018 GMC Sierra OBDII Code
Code P1478 2018 GMC Sierra comments
No comments found for this page.
Fix Your Car Smarter
Try the New AutoCodes App!
Get complete OBDII diagnostics, repair solutions, and cost estimates, plus AI chat support on demand.
