P1478 2017 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 2017 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 2017 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 2017 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 2017 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 2017 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.
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Frequently Asked Questions about P1478 2017 GMC Sierra Code
1. What does the OBDII code P1478 mean on a 2017 GMC Sierra?
P1478 indicates a high voltage issue in the Particulate Matter Sensor Temperature Circuit, which monitors the exhaust gas temperature to ensure proper operation of the diesel particulate filter (DPF).
2. What are the common symptoms of code P1478?
Symptoms may include the check engine light turning on, poor fuel efficiency, reduced engine performance, or the vehicle entering limp mode.
3. What causes the P1478 code to appear on a 2017 GMC Sierra?
Common causes include a faulty particulate matter (PM) sensor, damaged wiring or connectors in the temperature circuit, or a malfunctioning powertrain control module (PCM).
4. Can I drive my 2017 GMC Sierra with the P1478 code?
While the vehicle may still be drivable, operating it with this code could lead to further damage to the emissions system or reduced performance, so it’s best to address the issue promptly.
5. How do I diagnose the P1478 code on my vehicle?
Diagnosis involves checking the PM sensor and its wiring for damage, testing the circuit for proper voltage, and using a scan tool to monitor the sensor’s data.
6. How can I fix the P1478 code on my 2017 GMC Sierra?
Repairs may include replacing the PM sensor, repairing or replacing damaged wiring or connectors, or reprogramming or replacing the PCM if necessary.
7. How much does it cost to repair the P1478 code?
Repair costs can vary, but replacing a PM sensor typically costs between $200 and $600, depending on labor and parts. Wiring repairs or PCM replacement may increase the cost.
8. Can a dirty diesel particulate filter cause the P1478 code?
While a clogged DPF doesn’t directly cause this code, it can lead to related issues with the PM sensor, so it’s worth inspecting the DPF during diagnosis.
9. Will clearing the P1478 code with a scan tool fix the problem?
Clearing the code may temporarily turn off the check engine light, but the issue will likely return unless the underlying cause is addressed.
10. Is the P1478 code covered under warranty for a 2017 GMC Sierra?
This depends on your vehicle’s warranty terms. Emissions-related components like the PM sensor may be covered under the emissions warranty, so check with your dealer.
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