System: Powertrain | Standard: ISO/SAE Controlled | Fault type: General | Location: Bank 2
Definition source: SAE J2012/J2012DA (industry standard)
DTC P2935 indicates the powertrain control module has detected that the cylinder deactivation system is not enabling as commanded and is effectively “stuck off” on Bank 2. In other words, when operating conditions would normally allow deactivation, the system remains in full-cylinder mode. The exact strategy, components involved, and the conditions that must be met before deactivation is requested vary by vehicle, so confirmation steps should be performed using the correct service information. This code does not, by itself, prove a specific part has failed; it flags that the expected deactivation state change for Bank 2 did not occur or could not be verified.
What Does P2935 Mean?
P2935 – Cylinder Deactivation System – Stuck Off (Bank 2) means the engine control module has determined that the cylinder deactivation system for Bank 2 did not transition into the deactivated state when it was commanded or expected to do so. SAE J2012 defines how DTCs are structured and labeled, and this entry specifically points to a functional “stuck off” condition (deactivation not happening) rather than a specific “circuit high/low/open” electrical description. The module typically bases this determination on command status, feedback signals, and operating conditions; the precise inputs and validation logic vary by vehicle and should be verified in the applicable service documentation.
Quick Reference
- Subsystem: Cylinder deactivation control and feedback for Bank 2 (actuation hardware, oil control/flow elements where used, and related monitoring inputs).
- Common triggers: Deactivation requested but Bank 2 does not confirm the expected state change within the monitor’s criteria; repeated failed enable attempts; implausible feedback versus command.
- Likely root-cause buckets: Wiring/connector issues; actuator/solenoid or control valve issues; power/ground integrity problems; mechanical sticking in the deactivation mechanism; module/software or calibration factors (vehicle-dependent).
- Severity: Usually moderate; typically drivability may be normal but efficiency can drop. If accompanied by misfire, reduced power, or abnormal engine noise, treat as higher priority.
- First checks: Scan data for command vs feedback on Bank 2; check oil level/condition if the system is oil-pressure dependent (varies by vehicle); inspect connectors and harness routing; confirm no related misfire or oil pressure codes.
- Common mistakes: Replacing actuators/solenoids without verifying command and feedback data, ignoring power/ground voltage-drop checks, or overlooking mechanical sticking or oil supply issues where applicable.
Theory of Operation
Cylinder deactivation systems improve efficiency by disabling selected cylinders under light-load conditions. The control module decides when to enable deactivation based on inputs such as engine load, speed, temperature, and other criteria that vary by vehicle. When conditions are met, the module commands Bank 2 deactivation through one or more actuators (often solenoids or control valves) that alter valve lifter operation or similar mechanisms to prevent normal combustion events in the targeted cylinders.
The module then validates operation by monitoring feedback, which may include a dedicated position/state signal, changes in engine speed fluctuation patterns, manifold pressure response, or other plausibility indicators. P2935 sets when Bank 2 does not show the expected transition to the deactivated state, suggesting the system remains enabled for all cylinders on that bank despite a deactivation request.
Symptoms
- Check engine light: MIL illuminated, often after a drive cycle where deactivation would normally occur.
- Reduced fuel economy: Efficiency decreases because the engine remains in full-cylinder mode.
- Mode inoperative: Cylinder deactivation status shows “not active” or “disabled” for Bank 2 when conditions seem appropriate.
- Driveability changes: Mild hesitation, surging, or roughness if the system repeatedly attempts to enable and then aborts.
- Engine noise: Unusual ticking or valvetrain noise may be noticed if a mechanism is sticking (not proof of failure without testing).
- Related codes: Additional powertrain codes may accompany P2935, such as misfire, oil pressure, or actuator performance-related faults (vehicle-dependent).
Common Causes
- Harness or connector faults in the Bank 2 cylinder deactivation actuator control/feedback circuits (loose pins, corrosion, damaged insulation, poor pin fit)
- Open, short-to-ground, or short-to-power in wiring related to the Bank 2 cylinder deactivation solenoids/actuators
- Power supply or ground integrity issues feeding the cylinder deactivation actuators/valve assembly (including shared grounds)
- Bank 2 cylinder deactivation solenoid/actuator mechanically sticking or electrically failing (coil/internal fault), preventing commanded operation
- Oil condition or oil-pressure-related constraints that inhibit cylinder deactivation operation (varies by vehicle and strategy)
- Sensor input or plausibility issue that causes the control module to inhibit deactivation (for example, enabling-condition inputs; exact inputs vary by vehicle)
- Internal fault in the cylinder deactivation valve assembly/manifold (if equipped) affecting Bank 2 actuation
- Control module fault, calibration issue, or update needed that affects monitoring/commanding of cylinder deactivation (verify with service information)
Diagnosis Steps
Tools typically needed include a scan tool with live data and bi-directional controls (if supported), a digital multimeter, and basic back-probing leads. A wiring diagram and connector pinout for the cylinder deactivation system are essential. If accessible, a lab scope can help confirm command/response behavior, but many checks can be completed with live data plus voltage-drop testing.
- Confirm the DTC is P2935 and record freeze-frame and readiness information. Note operating conditions when it set (load, temperature, speed), because cylinder deactivation is commonly enabled only under specific conditions that vary by vehicle.
- Check for related DTCs (oil pressure, misfire, cam/crank correlation, VVT, power supply/ground, actuator control). Diagnose those first if they directly affect enable criteria or shared power/grounds, then re-check whether P2935 returns.
- Using the scan tool, review cylinder deactivation data PIDs (names vary), such as commanded mode versus actual/confirmed mode for Bank 2, and any status flags indicating “inhibited” or “not allowed.” If the system is inhibited, use service information to determine which prerequisite is not being met.
- Perform a visual inspection of the Bank 2 cylinder deactivation components and related harness routing. Look for oil saturation at connectors, chafing near brackets, heat damage, and evidence of prior repairs. Disconnect suspect connectors and inspect for spread terminals, corrosion, or backed-out pins.
- Clear codes and perform a controlled road test while logging relevant live data (commanded deactivation, actual deactivation status, enabling-condition flags). If the scan tool supports it, run the cylinder deactivation functional test under the required conditions and note whether Bank 2 fails to transition.
- With the fault present or while commanding the function, verify actuator power feed and ground integrity at the appropriate connector(s). Use voltage-drop testing on both the power side and the ground side under load (command active if possible) to identify high resistance that a static continuity test may miss.
- Check the control circuit(s) between the module and the Bank 2 actuator/solenoid(s) for opens and shorts. With the circuit isolated as required by service information, test for continuity end-to-end, short-to-ground, and short-to-power. Perform a wiggle test on the harness and connectors during measurements to expose intermittent faults.
- If service information allows, measure the electrical integrity of the Bank 2 actuator/solenoid(s) (for example, coil resistance) and compare between Bank 1 and Bank 2 components where applicable. A large discrepancy can indicate an internal electrical issue, but confirm with the specified test method and conditions.
- If electrical tests pass, evaluate whether the actuator or valve assembly is sticking mechanically. Use bi-directional controls to command on/off transitions and observe response. If the system consistently fails to transition on Bank 2 despite correct command and verified power/ground, a sticking actuator/valve assembly or related mechanical issue becomes more likely.
- Verify system prerequisites that can prevent deactivation operation (varies by vehicle), including oil condition and any monitored inputs that must be within limits. Do not assume an oil-related cause solely from this DTC; confirm by checking the enabling-condition indicators in live data and following service information.
- If wiring, connectors, power/ground, actuator integrity, and prerequisites all check out, follow service information for module-side checks. This may include verifying module outputs under command, pin-fit testing, and confirming whether a calibration update or module fault is suspected only after all external causes are eliminated.
Professional tip: Prioritize tests that compare “commanded” versus “actual/confirmed” cylinder deactivation status while simultaneously verifying voltage-drop on the actuator’s power and ground under load. This combination quickly separates an enable/logic inhibition from a true actuation failure and helps pinpoint high-resistance connections that can look fine during simple continuity checks.
Possible Fixes & Repair Costs
Repair costs for P2935 vary widely because the correct fix depends on what testing proves: a mechanical/hydraulic issue in the cylinder deactivation hardware, an electrical supply/ground problem, a control/feedback circuit fault, or a control-module command/strategy issue. Labor access and required parts also vary by vehicle.
- Repair damaged wiring, poor pin fit, or corrosion at connectors for the cylinder deactivation solenoid/valve, related sensors, or the engine control module
- Restore correct power and ground integrity to the cylinder deactivation system (clean/tighten grounds, repair splices, correct voltage-drop issues)
- Replace a cylinder deactivation solenoid/valve or actuator that fails functional testing (stuck closed/off or not responding to commanded operation)
- Service oil condition and correct any verified lubrication-related restrictions that prevent proper actuator movement (varies by vehicle design and service procedures)
- Repair or replace related control components (such as oil control valves or control passages) if testing shows the deactivation hardware cannot be commanded on
- Address confirmed sensor feedback issues (replace only if signal integrity and reference/ground are verified and the sensor fails validation tests)
- Update/reprogram or replace the control module only after all external circuits and components are proven good and service information supports it
Can I Still Drive With P2935?
Often the vehicle remains driveable, but performance, smoothness, and fuel economy can be affected because the cylinder deactivation system on Bank 2 is detected as stuck off. Avoid heavy loads and extended high-speed driving until diagnosed. If you also have reduced power warnings, abnormal vibration/misfire symptoms, oil-pressure warnings, overheating, stalling, or brake/steering warning lights, do not continue driving and have the vehicle inspected promptly.
What Happens If You Ignore P2935?
Ignoring P2935 can lead to ongoing fuel economy loss and drivability complaints, and it may mask related faults that develop as the control system continues to attempt operation. Prolonged operation with unresolved underlying issues (electrical integrity, actuator control, or lubrication problems) can increase wear risk and may result in additional diagnostic trouble codes and more complex repairs.
Related Codes
- P2934 – Cylinder Deactivation System – Stuck On (Bank 2)
- P2933 – Cylinder Deactivation System – Stuck Off (Bank 1)
- P2932 – Cylinder Deactivation System – Stuck On (Bank 1)
- P2931 – Fuel Pump Secondary Circuit Range/Performance
- P2930 – Fuel Pump Secondary Circuit High
- P2929 – Fuel Pump Secondary Circuit Low
- P2928 – Fuel Pump Secondary Circuit/Open
- P2927 – Fuel Cutoff Valve “B” Performance
- P2926 – Fuel Cutoff Valve “B” Control Circuit High
- P2925 – Fuel Cutoff Valve “B” Control Circuit Low
Key Takeaways
- P2935 indicates the cylinder deactivation system is detected as stuck off on Bank 2, not that a specific part is automatically bad.
- Diagnosis should be test-driven: verify command vs. response, electrical integrity, and any required enable conditions.
- Wiring/connector problems and power/ground integrity issues are common and should be checked before replacing actuators.
- Oil condition and system cleanliness can matter because many designs use oil pressure to move deactivation hardware.
- Module replacement or reprogramming should be considered only after external causes are ruled out.
Vehicles Commonly Affected by P2935
- Vehicles equipped with cylinder deactivation (variable displacement) engine technology
- Engines that use oil-pressure-actuated lifters or rocker mechanisms for cylinder deactivation
- Engines with electronically controlled oil control valves/solenoids dedicated to cylinder deactivation
- Configurations with separate cylinder banks (V-type engines) where Bank 2 monitoring is supported
- Vehicles frequently operated with extended oil change intervals or poor oil maintenance history
- Vehicles exposed to repeated short-trip operation where oil contamination/sludge risk is higher
- Higher-mileage vehicles where harness flex, connector fretting, or internal actuator wear is more likely
- Vehicles with recent engine repairs where connectors, grounds, or oil passages may have been disturbed
FAQ
Does P2935 mean the engine is permanently stuck in cylinder deactivation mode?
No. P2935 indicates the opposite condition is being detected: the cylinder deactivation system is stuck off on Bank 2 (it is not enabling when the module expects it to). The engine typically operates on all cylinders, but the system cannot transition as commanded under certain conditions.
Is P2935 an electrical problem or a mechanical problem?
It can be either, depending on what testing shows. A “stuck off” result may be caused by an actuator that does not move, oil-pressure/control issues that prevent movement, or an electrical problem (power, ground, control, or feedback signal integrity) that prevents proper actuation or causes the module to detect no response.
What is Bank 2, and why does it matter for this code?
Bank 2 refers to the cylinder bank that does not contain cylinder 1 on engines with two cylinder banks. P2935 is specifically tied to the cylinder deactivation system operation on that bank, so diagnosis should focus on the Bank 2 hardware, circuits, and any shared power/ground feeds that could affect it.
Will an oil change clear P2935?
An oil change alone may help only if testing and inspection indicate oil condition or contamination is contributing to actuator sticking or restricted control flow. The code should not be assumed to be an oil-only issue; electrical integrity checks and commanded function verification are still required.
How do I confirm the fix after repairs?
Clear the code, then verify with a road test or service procedure that the module can command cylinder deactivation and that the system response is present on live data (varies by vehicle). Recheck for pending codes and confirm that Bank 2 deactivation commands no longer result in a stuck-off detection.
For best results, base the final repair on confirmed test results (command versus response, circuit integrity, and oil/control flow checks) rather than replacing parts by guesswork.