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Cadillac · Known Issues

2021 Cadillac CT4 Problems: 7 Known Issues

2021 model year · NHTSA recalls, manufacturer TSBs, and owner forum reports · Updated September 2026

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Issue summary

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2021 Cadillac CT4 has 7 documented known issues, with 4 rated critical. The most serious are Daytime Running Lights May Stay On with Headlights (Recall 22V903), 10-Speed Transmission Damage Can Cause Wheel Lock-Up (Recall 25V148), Airbag Warning Lamp May Not Illuminate Consistently (Recall 21V421) and Roof-Rail Side-Curtain Airbags May Be Installed Incorrectly (Recall 21V611). Across all issues with published estimates, repair costs range from $400 to $1,800. DIY maintenance guides at au7o.io.

In This Article

  • CT4 Safety/Recalls2
  • CT4 Exterior1
  • CT4 Transmission1
  • CT4 Engine2
  • CT4 Suspension1
  • Recalls4
  • FAQ
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In This Article

  • Safety/Recalls2
  • Exterior1
  • Transmission1
  • Engine2
  • Suspension1
  • Recalls4
  • FAQ

All 7 Known Issues

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ALL YEARS202520242023202220212020

On the 2021 Cadillac CT4, on certain 2021 Cadillac CT4 vehicles, the communications gateway module can process loss of communication with the sensing and diagnostic module incorrectly, causing inconsistent illumination of the airbag malfunction indicator.

Common Symptoms

  • Open safety recall
  • Airbag warning lamp may not warn consistently

How to Fix

Check the VIN and recall completion history. Cadillac dealers update the communications gateway module software under recall N212338110.

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On the 2020-2022 Cadillac CT4, on certain 2020-2022 Cadillac CT4 vehicles, the roof-rail side-curtain airbags may not have been installed correctly and may deploy improperly in a crash.

Common Symptoms

  • Open safety recall
  • Side-curtain airbag installation concern

How to Fix

Check the VIN and recall status. Cadillac dealers inspect both roof-rail airbags and reinstall them as necessary under recall N212342780.

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On the 2020-2023 Cadillac CT4, on certain 2020-2023 Cadillac CT4 vehicles, the daytime running lights may not deactivate when the headlights are on, creating excess glare and failing FMVSS 108.

Common Symptoms

  • Open safety recall
  • Daytime running lights remain on with headlights

How to Fix

Check the VIN and recall status. The body-control-module software is updated by a dealer or over the air under recall N222386380.

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On the 2020-2021 Cadillac CT4, certain 2020-2021 Cadillac CT4 vehicles equipped with a 10-speed transmission can develop internal transmission damage that may cause the wheels to lock while driving.

Common Symptoms

  • Open safety recall
  • Unexpected wheel lock-up risk

How to Fix

Check the VIN and campaign status. Cadillac dealers install transmission-control-module monitoring software under recall N242480630; follow the campaign instructions if the software detects damage.

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On the 2020-2025 Cadillac CT4 LSY 2.0L Turbo I4, on the 2.0L turbo LSY four-cylinder used in the CT4 base/Luxury/Premium Luxury/Sport, oil weeps from what appears to be several places at once — the camshaft carrier cover, the engine front cover, the timing chain upper cover, and the lower oil pan. GM's own bulletin traces most of these to an improper amount of RTV sealant applied to the cam carrier cover gasket during engine assembly, so the leak is a manufacturing defect rather than normal gasket aging. Oil migrates down the front of the block and drips onto the subframe and exhaust, producing a burning-oil smell and low-oil messages between changes. Owners of both the CT4 and its LSY-engined sibling XT4 report the same leak, often re-appearing after a first repair attempt if the mating surfaces were not fully cleaned.

Common Symptoms

  • Oil drips on driveway under the front of the engine
  • Burning oil smell after driving
  • Oil residue visible on the front cover and camshaft carrier area
  • Low engine oil message between oil changes
  • Repair performed once but leak returns

How to Fix

Follow GM bulletin 21-NA-240: clean and dye-trace the engine to confirm the true origin before replacing anything, since the visible drip point is usually far below the source. The correct repair is to remove the camshaft carrier cover, completely strip the old sealant from both surfaces, and re-seal with the specified sealant bead and torque sequence; the front cover and oil pan are re-sealed only if independently confirmed leaking. Have this done under powertrain warranty if the vehicle still qualifies. Do not accept a simple 'add stop-leak' or 'monitor it' answer — the leak progresses.

Typical repair cost:$450 - $1,800

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Community Reported
High ConfidenceVerifiedReviewed Aug 2026

On the 2020-2025 Cadillac CT4 LSY 2.0L Turbo I4, the LSY 2.0L turbo routes crankcase vapors through a PCV/crankcase pressure sensor mounted in the valve cover area. In cold climates and on short-trip driving, water vapor condenses in the sensor port and hose and then freezes, blocking the reference passage. The ECM sees an implausible crankcase pressure signal and sets P04FB (Crankcase Ventilation Hose Connection Sensor Range/Performance), lighting the check engine light. Because the ice thaws once the car sits in a warm shop, dealers frequently find 'no problem found' and simply clear the code, and some replace the sensor unnecessarily. GM addressed it in a preliminary information bulletin covering CT4 and other LSY-equipped vehicles.

Common Symptoms

  • Check engine light appears in cold weather
  • Code returns after clearing during winter
  • No driveability symptom other than the MIL
  • Dealer reports 'no problem found'

How to Fix

Per GM's PIP5841-series diagnostic tip, do not replace the sensor on the first occurrence. Remove the crankcase pressure sensor and hose assembly, inspect for frozen moisture or ice, allow it to thaw and drain completely, then clear all residual moisture with low-pressure compressed air and a shop towel before reinstalling. Check the PCV hose routing for low spots that trap condensate. If the code returns repeatedly in warm weather, then diagnose the sensor and the PCV/valve cover assembly itself. Longer drive cycles that fully warm the engine reduce recurrence.

Typical repair cost:$0 - $350

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Community Reported
High ConfidenceVerifiedReviewed Aug 2026

On the 2020-2024 Cadillac CT4, cT4 owners across trims report a distinct pop, thump or creak from one or both front corners when crossing driveway dips, manhole covers, speed bumps, or during sharp low-speed steering maneuvers. The Alpha 2 front suspension uses a double-pivot strut arrangement, and the noise has been traced by owners and dealers to individual defective front struts — in several cases the strut body was found wet with damper fluid — as well as to strut mount and bushing seating. GM has circulated engineering-information requests asking technicians to complete a checklist when a popping or thump-type noise is heard from the front suspension during sharp maneuvers, which indicates GM is collecting field data on a recognized pattern rather than treating each car as a one-off. Many owners are told nothing is wrong on the first visit even when the technician can hear the noise.

Common Symptoms

  • Pop or thump from a front corner over small bumps
  • Creaking from the front struts over speed bumps
  • Noise during sharp low-speed steering
  • Damper fluid visible on the strut body
  • Noise worsens after roughly 20,000 miles

How to Fix

Insist the dealer complete GM's front-suspension noise checklist and road-test with a technician in the car rather than relying on a shop-floor bounce test. Inspect both front struts for damper fluid on the body — a wet strut is a warranty replacement. If the struts are dry, check the strut mount bearing, the upper mount fasteners and the lower control arm bushings, and verify all suspension fasteners were torqued at ride height, not on the hoist. Replace the offending strut assembly; owners who had a single defective strut replaced report the noise gone.

Typical repair cost:$400 - $1,300

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Medium ConfidenceVerifiedReviewed Aug 2026
NHTSA Recalls4 recalls

POWER TRAIN:AUTOMATIC TRANSMISSION

General Motors LLC (GM) is recalling certain 2019-2020 Cadillac CT6, 2020-2021 CT4, CT5, and 2020-2022 Chevrolet Camaro vehicles equipped with a 10-speed transmission. The transmission may become damaged internally and cause the wheels to lock-up.

Campaign #25V14800006/03/2025

EXTERIOR LIGHTING:LIGHTING CONTROL MODULE:SOFTWARE

General Motors, LLC (GM) is recalling certain 2020-2023 Cadillac CT4 and CT5; 2021-2023 Buick Envision; and 2022-2023 Cadillac Escalade and Escalade ESV, Chevrolet Silverado 1500, Suburban, Tahoe, GMC Sierra 1500, Yukon, and Yukon XL vehicles. The daytime running lights (DRLs) may not deactivate when the headlights are on. As such, these vehicles fail to comply with the requirements of Federal Motor Vehicle Safety Standard number 108, "Lamps, Reflective Devices, and Associated Equipment."

Campaign #22V90300008/12/2022

AIR BAGS:SRS MALFUNCTION WARNING LAMP/LIGHT

General Motors, LLC (GM) is recalling certain 2021 Buick Envision, Cadillac CT4, CT5, Escalade, Escalade ESV, Chevrolet Tahoe, Corvette, Suburban, GMC Yukon, Yukon XL vehicles. The communications gateway module incorrectly processes a loss of communication with the sensing diagnostic module (SDM), causing the air bag malfunction indicator light to inconsistently illuminate.

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Other Cadillac Models

Cadillac XTS30Cadillac CT524Cadillac Escalade20Cadillac Lyriq19Cadillac XT617Cadillac CT617

Frequently Asked Questions

What are the most common Cadillac CT4 problems?

According to Au7o's research across NHTSA recalls, manufacturer TSBs, and owner forum reports, the 2021 Cadillac CT4 has 7 documented issues. The most frequently reported are: Daytime Running Lights May Stay On with Headlights (Recall 22V903), 10-Speed Transmission Damage Can Cause Wheel Lock-Up (Recall 25V148), Airbag Warning Lamp May Not Illuminate Consistently (Recall 21V421). Of these, 4 are rated critical and should be addressed promptly.

Is the Cadillac CT4 reliable?

The 2021 Cadillac CT4 has 7 known issues compiled from NHTSA recalls, manufacturer TSBs, and owner forum reports. 4 issues are rated critical: Daytime Running Lights May Stay On with Headlights (Recall 22V903) and 10-Speed Transmission Damage Can Cause Wheel Lock-Up (Recall 25V148) and Airbag Warning Lamp May Not Illuminate Consistently (Recall 21V421) and Roof-Rail Side-Curtain Airbags May Be Installed Incorrectly (Recall 21V611). Prospective buyers should inspect for these issues and factor potential repair costs into their purchase decision. Regular maintenance following the manufacturer's schedule helps prevent many common problems.

How much does it cost to fix common Cadillac CT4 problems?

Repair costs for known Cadillac CT4 issues range from $0 to $1,800, depending on the specific problem and whether you choose DIY or professional repair. Au7o provides step-by-step DIY maintenance guides that can help reduce repair costs.

What is the 2020-2023 Cadillac CT4 Daytime Running Lights May Stay On with Headlights (Recall 22V903)?

On certain 2020-2023 Cadillac CT4 vehicles, the daytime running lights may not deactivate when the headlights are on, creating excess glare and failing FMVSS 108. Severity: high.

What is the 2020-2021 Cadillac CT4 10-Speed Transmission Damage Can Cause Wheel Lock-Up (Recall 25V148)?

Certain 2020-2021 Cadillac CT4 vehicles equipped with a 10-speed transmission can develop internal transmission damage that may cause the wheels to lock while driving. Severity: high.

Content on this page was compiled with AI assistance using NHTSA complaints, TSBs, owner reports, and public automotive data. While we strive for accuracy, this information may contain errors. Always verify repair procedures and specifications with your vehicle's service manual or a qualified mechanic.

Data compiled from NHTSA recalls, manufacturer TSBs, automotive forums, and AI-assisted research. No aggregated owner-report counts available for this vehicle yet.

Campaign #21V42100010/06/2021

AIR BAGS:SIDE/WINDOW:CURTAIN

General Motors, LLC. (GM) is recalling certain 2020-2022 Cadillac CT4 and CT5 vehicles. The roof rail side-curtain air bags may not have been installed correctly, which could result in an improper air bag deployment during a crash.

Campaign #21V61100005/08/2021

Enter your VIN at NHTSA.gov to check recalls specific to your vehicle.

What is the 2021 Cadillac CT4 Airbag Warning Lamp May Not Illuminate Consistently (Recall 21V421)?

On certain 2021 Cadillac CT4 vehicles, the communications gateway module can process loss of communication with the sensing and diagnostic module incorrectly, causing inconsistent illumination of the airbag malfunction indicator. Severity: high.

What is the 2020-2022 Cadillac CT4 Roof-Rail Side-Curtain Airbags May Be Installed Incorrectly (Recall 21V611)?

On certain 2020-2022 Cadillac CT4 vehicles, the roof-rail side-curtain airbags may not have been installed correctly and may deploy improperly in a crash. Severity: high.

What is the 2020-2024 Cadillac CT4 Front Strut Popping and Thump Noise Over Small Bumps?

CT4 owners across trims report a distinct pop, thump or creak from one or both front corners when crossing driveway dips, manhole covers, speed bumps, or during sharp low-speed steering maneuvers. The Alpha 2 front suspension uses a double-pivot strut arrangement, and the noise h… Repairs typically run $400-$1,300. Severity: medium.

What is the 2020-2025 Cadillac CT4 LSY 2.0T Cam Carrier Cover Sealant Defect Causes Engine Oil Leaks?

On the 2.0L turbo LSY four-cylinder used in the CT4 base/Luxury/Premium Luxury/Sport, oil weeps from what appears to be several places at once — the camshaft carrier cover, the engine front cover, the timing chain upper cover, and the lower oil pan. GM's own bulletin traces most… Repairs typically run $450-$1,800. Severity: medium.

What is the 2020-2025 Cadillac CT4 Crankcase Pressure Sensor Ices Over in Cold Weather Setting P04FB?

The LSY 2.0L turbo routes crankcase vapors through a PCV/crankcase pressure sensor mounted in the valve cover area. In cold climates and on short-trip driving, water vapor condenses in the sensor port and hose and then freezes, blocking the reference passage. The ECM sees an impl… Repairs typically run $0-$350. Severity: low.