AutoCodes – Buick – P0873 Buick

P0873 Buick Code - Transmission Fluid Pressure Switch 3 Circuit High Voltage

Quick Answer

The transmission fluid pressure switch, also known as the pressure switch manifold, is a multiple switch assembly made up of 3 normally open pressure switches and 1 normally closed pressure switch. Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly. 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
P0873 Buick indicates Transmission Fluid Pressure Switch 3 Circuit High Voltage.
Common causes
Common causes include Low transmission fluid level, Dirty transmission fluid, Faulty Transmission Control Solenoid Valve Assembly.
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 529
How popular is this code, among other codes? Low
Table of contents Created and updated by William Orellana on Aug 02, 2022
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Code P0873 Buick Description

The transmission fluid pressure switch, also known as the pressure switch manifold, is a multiple switch assembly made up of 3 normally open pressure switches and 1 normally closed pressure switch. Pressure switch 1 monitors shift valve 1 positioning, pressure switch 2 monitors shift valve 2 positioning, pressure switch 3 monitors shift valve 3 positioning, and pressure switch 4 monitors the position of the manual selector valve. The TCM provides a signal circuit to each of the pressure switches. The TCM constantly monitors the circuits to determine the position of the shift valves. The position of shift valves 1, 2, and 3 is controlled by 3 normally closed shift solenoids. When energized, shift solenoid 1 directs fluid pressure to shift valve 1, shift solenoid 2 directs fluid pressure to shift valve 2, and shift solenoid 3 directs fluid pressure to shift valve 3, which strokes the shift valves. When a shift valve is stroked, an exhaust passage is blocked and fluid pressure increases, closing the normally open pressure switch. The Diagnostic Trouble Code (DTC) will be set when the TCM detects that transmission fluid pressure switch 3 signal circuit is High when shift solenoid 3 is commanded ON for 1 s.
OBDII Code P0873 Buick - Transmission Fluid Pressure Switch 3 Circuit High Voltage - AutoCodes.com
P0873 Buick Code - Transmission Fluid Pressure Switch 3 Circuit High Voltage

What are the Possible Causes of the DTC P0873 Buick?

  • Low transmission fluid level
  • Dirty transmission fluid
  • Faulty Transmission Control Solenoid Valve Assembly
  • Transmission Control Solenoid Valve Assembly harness is open or shorted
  • Transmission Control Solenoid Valve Assembly circuit poor electrical connection
  • Faulty Transmission Control Module (TCM)

How to Fix the DTC P0873 Buick?

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 P0873 Buick 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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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 P0873 Buick Code

1. What does the OBDII code P0873 mean on a Buick?

P0873 indicates that the Transmission Control Module (TCM) has detected a high voltage issue in the transmission fluid pressure switch 3 circuit.

2. What are common symptoms of the P0873 code on a Buick?

Symptoms may include harsh or delayed shifting, the transmission going into limp mode, poor acceleration, or the check engine light being illuminated.

3. What causes the P0873 code on a Buick?

Common causes include a faulty transmission fluid pressure switch, damaged wiring or connectors in the circuit, low or contaminated transmission fluid, or a malfunctioning TCM.

4. Can low transmission fluid cause a P0873 code in a Buick?

Yes, low or contaminated transmission fluid can affect the pressure readings and trigger the P0873 code.

5. How is the P0873 code diagnosed on a Buick?

A technician will visually inspect the wiring and connectors, check the transmission fluid level and condition, and use a scan tool to monitor the pressure switch circuit and confirm the fault.

6. Can I still drive my Buick with the P0873 code active?

Driving with this code is not recommended, as it may cause further damage to the transmission or lead to unsafe driving conditions due to shifting problems.

7. How do I fix the P0873 code on a Buick?

Repairs may involve replacing the faulty pressure switch, repairing or replacing damaged wiring or connectors, flushing and refilling the transmission fluid, or reprogramming the TCM if necessary.

8. How much does it cost to repair the P0873 code on a Buick?

The cost depends on the root cause but may range from $100 to $300 for simple fixes like a pressure switch replacement, or higher if extensive wiring or TCM repairs are needed.

9. Can a bad TCM cause the P0873 code in a Buick?

Yes, a malfunctioning Transmission Control Module can cause incorrect voltage readings and trigger the P0873 code.

10. Will clearing the P0873 code fix the issue?

Clearing the code may temporarily remove the check engine light, but the underlying issue must be addressed to prevent the code from reappearing.

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