P0842 on Chevrolet: How to Diagnose & Fix
Transmission Fluid Pressure Sensor/Switch 'A' Circuit Low
1 Chevrolet model · 1 documented issue · 1 critical · $300-$1,600 repair
P0842 on Chevrolet by model: symptoms, diagnosis and fix
P0700 is not a specific fault by itself — it is an umbrella/MIL-request code the ECM stores whenever the transmission control module (TCM) detects an internal transmission problem and asks the ECM to turn on the check-engine light. On the Silverado 1500 it almost always appears alongside more specific companion codes, and the underlying failure follows two dominant, well-documented patterns depending on the transmission. On trucks with the 6L80 six-speed automatic (2007-onward 5.3L and 6.2L V8 models), the internal TEHCM (Transmission Electro-Hydraulic Control Module — GM's combined valve body, solenoids, pressure switches, and TCM in a single pan-mounted unit) develops internal circuit-board/solenoid faults from heat and fluid degradation, throwing P0700 together with codes like P0796, P0777, P0842, or P0973 and dropping the truck into limp mode. On older/base trucks with the 4L60E four-speed (4.3L/4.8L), the same P0700 is typically triggered by a failed shift solenoid (P0753/P0758) or a faulty internal mode switch. Because P0700 is a stored 'passenger' code, a scan tool that can talk to the TCM (not just a basic reader) is required to pull the specific sub-code that identifies the actual failed component.
Common Symptoms
- Check engine light on with P0700 stored
- Transmission stuck in limp mode / limited to one gear (often 3rd or 5th)
- Harsh or delayed shifts
- Transmission fails to shift or slips
- Torque converter clutch not locking up / shudder
- No movement or won't shift out of park in severe cases
How to Fix
Do NOT replace parts off the P0700 alone. Use a bidirectional/TCM-capable scan tool to read the companion codes stored in the transmission controller and verify transmission fluid level and condition first (low or burnt DEXRON-VI fluid alone can trigger the chain). For 6L80 trucks, a failed internal TEHCM is confirmed by multiple simultaneous solenoid/pressure codes; the fix is to drop the pan and replace the TEHCM, which MUST then be programmed to the vehicle's VIN with GM calibration files before the truck will start or shift correctly (ordering the OEM unit by the last 8 VIN digits can yield a plug-and-play unit needing no fast-adapt relearn). For 4L60E trucks, replace the specific failed shift solenoid or internal mode switch identified by the sub-code. Repair the wiring/connectors to the TCM if corrosion is found. On very new 2023-2025 Silverado 1500s, P0700 paired with P0747 is a known valve-body defect covered by Safety Recall N242454440 / Special Coverage N242454441 — check the VIN with a dealer for a free repair.
Sources for this issue (1)
P0842 code reference
General diagnostic-code context. The code alone does not confirm a cause for your vehicle; use the applicable issue card and its sources.
Frequently asked questions
What does P0842 mean on a Chevrolet?
P0842 stands for "Transmission Fluid Pressure Sensor/Switch 'A' Circuit Low." The transmission fluid pressure sensor/switch 'A' circuit voltage is below the expected range (too low / shorted to ground). On Chevrolet it is documented across 1 model: Silverado 1500.
What are the most common causes of P0842?
The most common causes of P0842 are: Sensor signal shorted to ground, Faulty pressure sensor/switch A, Corroded/damaged connector, Internal TCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0842 on a Chevrolet?
Published repair estimates on Chevrolet range from $300 to $1,600 depending on the model and root cause. If an issue mentions a recall or campaign, check your VIN with the manufacturer or NHTSA and confirm eligibility and coverage with a dealer.
Looking for P0842 on a different make?
View P0842 across all makes →Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.