P0843 on 2006-2013 Chevy Silverado 1500: Transmission Pressure Sensor Fixes

What's Unique About the 2006-2013 Chevrolet SILVERADO 1500

The 2006-2013 Silverado 1500 spans two distinct transmission designs, which completely changes the repair for this code. Earlier models with the 4-speed 4L60-E transmission have a simple, replaceable pressure switch assembly. Later models with the 6-speed 6L80 integrate these switches into the main computer inside the transmission (the TEHCM). This makes the 6-speed repair significantly more complex and expensive, as the entire computer module must be replaced and programmed.

Diagnostic Flowchart

Tap your situation to follow the diagnostic path that matches what you're seeing on this vehicle. 👇

Generation note: This range covers two key generations of Silverado and their transmissions: - GMT800 / early GMT900 (approx. 2006-2008): Primarily equipped with the 4-speed 4L60-E/4L65-E/4L70-E automatic transmission. The fix targets the Pressure Switch Manifold (PSM). - Later GMT900 (approx. 2009-2013): Primarily equipped with the 6-speed 6L80 automatic transmission. The fix targets the Transmission Electro-Hydraulic Control Module (TEHCM).

Symptoms You May Notice

• Harsh, abrupt, or delayed shifting.
• Transmission is stuck in one gear (e.g., 2nd or 3rd), also known as 'limp mode'.
• Check Engine Light is illuminated.
• Inability to engage reverse.
• Sluggish acceleration.
• Transmission may seem to neutralize between shifts.
• Flashing 'D' (Drive) light on the instrument cluster.

Most Likely Causes

1. Failed Transmission Fluid Pressure Switch Manifold (PSM) 🔴 High Probability → Shop Transmission Assembly Applies to models with the 4-speed (4L60-E/4L65-E) transmission. The plastic manifold and its integrated switches are located inside the hot transmission pan and can become brittle and fail electrically over time. This is the most common failure point for P0843 on these models.
   How to confirm: After dropping the transmission pan, the PSM is visible on the valve body. A diagnostic scan tool can monitor the switch states; a switch that never changes its reading is faulty. The part is relatively inexpensive, so it's often replaced preventatively if other internal work is being done.
   Typical fix: Replace the Pressure Switch Manifold. It is highly recommended to also replace the transmission pan gasket and the internal wiring harness at the same time.
   Est. part cost: $40-$70
2. Failed Transmission Electro-Hydraulic Control Module (TEHCM) 🔴 High Probability → Shop Transmission Assembly Applies to models with the 6-speed (6L80) transmission. The pressure switches are integrated into the TEHCM circuit board. 🎬 See how to test and rebuild the 6L80 TEHCM circuits. Heat and vibration cause the internal laminated switch diaphragms to crack or the circuits to fail electrically, triggering the code.
   How to confirm: Diagnosis requires a high-level scan tool to confirm the pressure switch circuit within the TEHCM is reporting a constant high voltage. The presence of multiple pressure switch or solenoid codes simultaneously strongly points to TEHCM failure.
   Typical fix: Replace the entire TEHCM assembly located inside the transmission. The new TEHCM must be programmed to the vehicle's VIN using a J2534 interface tool and manufacturer software. Some specialists offer a service to clone your old module's programming to a new or remanufactured one.
   Est. part cost: $250-$500
3. Damaged Internal Wiring Harness 🟡 Medium Probability The wiring harness inside the transmission pan is exposed to hot fluid, which can make it brittle over time. Wires can break or connectors can fail, leading to an open circuit and a 'Circuit High' code. It is considered best practice to replace this harness whenever the pan is off for a PSM replacement on 4-speed models.
   How to confirm: Visually inspect the wiring harness for cracks, brittleness, or damage after removing the transmission pan. Check for continuity on the relevant wires with a multimeter.
   Typical fix: Replace the internal transmission wiring harness. This is often done at the same time as a PSM replacement on 4-speed models.
   Est. part cost: $50-$100
4. Low or Contaminated Transmission Fluid ⚪ Low Probability → Shop Transmission Assembly
   How to confirm: Check the transmission fluid level and condition. While this is less likely to cause a 'Circuit High' fault, which is purely electrical, extremely low or dirty fluid can cause erratic transmission behavior and trigger various codes.
   Typical fix: Perform a transmission fluid and filter change using the correct DEXRON-VI fluid.
   Est. part cost: $100-$200

Rare But Worth Checking

• Damaged External Wiring or Connector: A wire in the main harness leading to the transmission could be chafed or shorted to a power source. This can happen if the harness is rubbing against the chassis or exhaust. The main round connector on the 6L80 can also be a source of issues if not fully seated.
• Faulty Powertrain Control Module (PCM) or Transmission Control Module (TCM): → Shop Transmission Assembly This is very rare. The control module itself can fail, but all other potential causes, especially the internal components, should be ruled out first.

Diagnosis Steps

1. Check the transmission fluid level and condition. Ensure it is clean, at the correct level, and does not smell burnt. Use only DEXRON-VI fluid.
2. Use a scan tool to check for any other transmission-related trouble codes. Note codes that often appear with P0843, as multiple codes strongly suggest a TEHCM or harness failure.
3. Inspect the external transmission wiring harness and main connector for any visible damage, corrosion, or loose connections. On 6L80 models, ensure the main round connector is fully seated and locked.
4. Determine if your vehicle has the 4-speed (4L60-E family) or 6-speed (6L80) transmission to identify the correct internal components.
5. Drop the transmission oil pan and filter.
6. For 4-speed (4L60-E): Visually inspect the Pressure Switch Manifold (PSM) and its wiring harness for damage. It is the most likely culprit. Best practice is to replace both the PSM and the internal harness.
7. For 6-speed (6L80): The pressure switches are part of the TEHCM. A 'Circuit High' code almost always points to an internal TEHCM failure. While repair kits for the switch diaphragms exist (e.g., from Sonnax), they only fix the hydraulic seal and not an electrical failure, which is what P0843 indicates.
8. Test the circuit with a multimeter if possible to confirm an open or short, but often the most practical step is to replace the suspect component (PSM or TEHCM).
9. After replacement, refill with fresh DEXRON-VI fluid, clear the codes, and perform a test drive. If the TEHCM was replaced, it must be programmed to the vehicle's VIN before it will function.

Parts You'll Likely Need

• Transmission Fluid Pressure Switch Manifold (OEM #24215111) — This is the most common fix for P0843 on models with the 4-speed 4L60-E/4L65-E/4L70-E transmission (approx. 2006-2008).
  Trusted brands: ACDelco, Rostra, Standard Motor Products (SMP)
  OEM price range: $50-$70
  Aftermarket price range: $35-$55
• Transmission Electro-Hydraulic Control Module (TEHCM) (OEM #Varies by VIN/Tag ID (e.g., 24256939, 24275873, 24264141)) — This is the required fix for models with the 6-speed 6L80 transmission (approx. 2009-2013), as the pressure switches are integrated into this module. Must be programmed after installation.
  Trusted brands: ACDelco (New or Remanufactured), Sonnax (Remanufactured), Street Smart Transmission (Remanufactured)
  OEM price range: $400-$600
  Aftermarket price range: $280-$450 (Remanufactured)

Related Codes That Often Appear With This One

• P0700 — This is a generic code indicating that the Transmission Control Module (TCM) has requested the Check Engine Light to be turned on. It will almost always be present with any specific transmission code like P0843.
• P0848, P0873, P0877 — These are 'Circuit High' codes for other pressure switches (B, C, D, etc.). If multiple appear together, it strongly suggests a failure of the common component—either the PSM or the TEHCM—or its wiring harness.
• P0751, P0756 — These are shift solenoid performance codes. A failing TEHCM can cause these codes to appear alongside pressure switch codes, further pointing to a complete module failure rather than an individual solenoid.

Technical Service Bulletins (TSBs) & Recalls

• Bulletin #PIP4379M: This is a general diagnostic bulletin from GM that lists P0843 among many other codes that can be set due to various powertrain issues. It advises technicians to follow the standard diagnostic procedures for code P0701 first when multiple codes are present, indicating it's a starting point for a broader diagnosis rather than a specific fix for P0843 alone.

Platform-Specific Known Issues

• Owner Experience (6L80): The Cluster of Codes: Owners of 6L80-equipped Silverados often report that P0843 does not appear alone. It is frequently accompanied by other pressure switch codes (P0848, P0877) and/or solenoid performance codes (P0751, P0756). This pattern is a strong indicator of an internal TEHCM failure, not a problem with a single component.
• Owner Experience (4L60-E): The 'Might as Well' Repair: On forums dedicated to GM trucks, a common piece of advice for a P0843 code on a 4L60-E is to replace the internal wiring harness at the same time as the Pressure Switch Manifold. The harness is inexpensive and is subjected to the same heat and fluid that causes the PSM to fail, making its replacement a wise preventative measure to avoid having to drop the pan a second time.

Mechanic-Grade Diagnostic Values

• TFP Sensor/Switch 'A' Signal Voltage (KOEO) — expected: Switches between 0V and 5V depending on state. A variable sensor would be ~0.5V (low pressure) to ~4.5V (high pressure).. Failure: A sustained reading above 4.5V, typically stuck at 5.0V, indicates a 'Circuit High' fault.
• TFP Sensor Reference Voltage (Vref) at harness connector — expected: ~5.0 V. Failure: Significantly lower or higher voltage indicates a PCM or wiring issue.
• 4L60-E Shift Solenoid Resistance (1-2 or 2-3) — expected: 20 - 40 ohms at 68°F. Failure: Reading outside this range indicates a failed solenoid.
• 6L80 Pressure Control (PWM) Solenoid Resistance — expected: 3.0 - 8.0 ohms. Failure: Reading outside this range indicates a failed solenoid within the TEHCM.
• 6L80 On/Off Shift Solenoid Resistance — expected: 20 - 40 ohms. Failure: Reading outside this range indicates a failed solenoid within the TEHCM.

Scan Tool Commands That Help

• GM Tech 2 / GDS2 or equivalent: Live Data > Transmission Data > Pressure Switch Status (A, B, C, D, E) — To verify if the 'A' switch is stuck in one state (ON or OFF) while other switches change state during commanded gear changes. This confirms the fault is isolated to the 'A' circuit.
• GM Tech 2 / GDS2 or equivalent: Service Functions > Transmission Adaptive Pressure Learn (Fast Learn) — This procedure is required after replacing the TEHCM to calibrate the new module to the transmission's clutches and prevent harsh shifting.
• GM Tech 2 / GDS2 or equivalent: Solenoid Automated Cleaning Process — Can be used as a diagnostic or preliminary repair step if solenoid performance codes are also present, as it cycles all solenoids to flush out potential debris.

Wiring & Ground Locations

• 6L80 Main Connector — 16-pin round connector on the passenger side of the transmission case.. This is the single point of connection for all electronic signals between the vehicle's main harness and the internal TEHCM. A poor connection, corrosion, or pushed-out pin here can mimic an internal component failure.
• 4L60-E Main Connector — 20-pin round connector on the passenger side of the transmission case.. This connector contains the pins for the TFP manifold pressure switch. The circuit can be tested for opens or shorts here without dropping the transmission pan.
• 6L80 TEHCM Pressure Switch Pins — On the TEHCM circuit board itself, accessible after removing the valve body.. A technician can perform a direct continuity test on the pressure switches here. A video guide shows the ground pin is on the far right of the switch bank, allowing for a bench test of each switch to see if it opens and closes correctly.

When the Usual Fixes Don't Work

• While the most common cause for P0843 is a failed component inside the transmission (PSM or TEHCM), this is not always the case. If the component is replaced and the code persists, the fault likely lies in the wiring harness. A key diagnostic step is to disconnect the main transmission connector and test the vehicle-side harness pin for the TFP 'A' circuit. If voltage (typically 5V or 12V) is still present on that signal wire with the transmission disconnected, it indicates a short-to-power somewhere in the harness between the TCM/PCM and the transmission, and the transmission itself is not the cause of the code.

OEM Part Supersession History

• 24256939, 24257213, 24259835, 24261870, 24264141, 24275873, etc. → Varies; often replaced by remanufactured units like Sonnax GM6L-TEHCM-C6. — Revisions to address common failure points like pressure switch durability and solenoid performance.
  Heads up: TEHCMs are NOT interchangeable between certain year groups. Installing a TEHCM with the wrong Tag ID or from an incompatible year can result in a no-start condition, immediate limp mode, or programming failure. The vehicle's VIN must be used to source the correct part.

Model Year Variations Within This Range

• 2009-2010 (approx.): Early 6L80 TEHCMs (Gen 1) are known to be more susceptible to pressure switch failures and TCC solenoid issues due to heat.
• 2011+ (approx.): Later 6L80 TEHCMs feature improved solenoids, updated logic, and better thermal tolerance. However, they have different internal calibration and are not backward-compatible with earlier models without correct programming.