P26B7: How to Diagnose & Fix — Engine Coolant Bypass Valve "C" Control Circuit/Open
3 vehicles · 2 makes · $700-$1,800 repair
How to diagnose and fix P26B7: most-reported vehicles
Ranked by owner reports. Each card gives the symptoms, how to confirm the cause, the fix, parts and sources for that vehicle.
Jaguar F-PACE · 2017–2023
The Ingenium 2.0L and 3.0L engines in the F-PACE suffer from premature water pump failures. The pump bearing seizes or the impeller separates, causing rapid coolant loss and overheating that can warp the cylinder head if not caught immediately.
Common Symptoms
- Coolant warning light on dashboard
- Overheating in traffic
- Coolant puddle under engine
- Whining noise from water pump area
- Steam from engine bay
How to Fix
Replace the water pump and thermostat assembly. Use the updated JLR part number with reinforced bearing and impeller. Flush the cooling system and refill with Jaguar-specified OAT coolant.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Jaguar JDE40573 water-pump assembly for the early 2.0L gasoline branchOEMJDE40573
Confirmed main water-pump leakage/bearing failure on the cataloged 2018-2020 2.0L gasoline F-PACE branch Fitment/availability: JDE40573 replaces JDE38596/JDE40455 and is cataloged for the F-PACE 2.0L gasoline engine, 2018-2020, to chassi…
- T4A41037 water pump for the 3.0L AJ20P6 inline-six branchOEMT4A41037
Confirmed weep-chamber leak or mechanical pump failure on the later 3.0L AJ20P6 F-PACE branch Fitment/availability: T4A41037/LR121418 is the pump identified by JLR for the AJ20P6 3.0L gasoline inline-six and the retailer lists F-PACE thr…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningPull over immediately if the temperature gauge spikes. The Ingenium head warps quickly once overheated, turning a $1,200 water pump job into a $5,000+ head gasket repair.
Jaguar XE · 2017–2023
The water pump on the Ingenium 2.0L engine in the XE fails prematurely due to bearing wear and impeller separation. Coolant leaks from the pump weep hole as the seal degrades, eventually leading to complete failure and overheating if not addressed.
Common Symptoms
- Coolant leak from water pump weep hole
- Overheating warning
- Whining noise from front of engine
- Coolant puddle under car after parking
- Temperature gauge rising in traffic
How to Fix
Replace the water pump assembly with the updated JLR part. Include a new thermostat and coolant flush. Use OAT coolant only. Monitor coolant level closely for the first 500 miles after replacement.
What you need to fix it
Only diagnosis- and fitment-reviewed repair parts are linked here.
- Genuine Jaguar JDE40572 water-pump assembly for the 2.0L diesel branchOEMJDE40572
Confirmed main water-pump leakage or bearing/impeller failure on a 2017-2019 U.S. Confirm VIN/current supersession; it is not for the 2.
- Genuine Jaguar JDE40573 water-pump assembly for the early 2.0L gasoline Ingenium branchOEMJDE40573
Confirmed main water-pump leakage or bearing/impeller failure on the cataloged 2018-2020 2.0L gasoline XE branch Fitment/availability: JDE40573 replaces JDE38596/JDE40455 and includes the seal. Confirm XE VIN, production break and curren…
- Genuine Jaguar AJ813909 water-pump assembly for the 3.0L supercharged V6 branchOEMAJ813909
Confirmed mechanical water-pump leakage or bearing failure on a 2017-2020 XE 3.0L supercharged V6 Fitment/availability: AJ813909 is the current supersession chain listed for 3.0L 2017-2020 applications and includes the gasket. Confirm VI…
As an Amazon Associate, we earn from qualifying purchases; other part links may also earn au7o a commission. Confirm fitment by VIN before buying.
Owner tips & cautions
- WarningCheck for a small coolant drip under the front of the car after every drive. Catching the water pump early saves the head gasket.
Jeep Grand Cherokee · 2012–2021
Oil found around the Pentastar oil filter adapter does not prove that the complete adapter or oil cooler has cracked. FCA's service guidance separates several repair paths: a cap O-ring that is cut, damaged, or installed in the wrong groove; five adapter bolts that are not at the specified torque; and a confirmed leak at the adapter-to-block O-rings and gaskets. FCA's 2021 guidance tells technicians to reseal a confirmed interface leak rather than replace the adapter on the covered non-2014 vehicles, while model-year 2014 is handled as an adapter-replacement exception. The previous card treated 2011-2020 vehicles alike, prescribed an aluminum assembly, implied oil/coolant cross-contamination, and listed P0128 and P26B7 without reviewed support.
Common Symptoms
- Oil visible around the oil-filter cap or adapter
- Oil collecting in the engine valley or running down the engine
- A leak that reappears in dye tracing at the adapter-to-block interface
How to Fix
Clean the area and add approved oil dye so the source can be observed before parts are ordered. Inspect the oil-filter-cap O-ring for damage and confirm it is seated in the correct groove. Check the five oil-filter-adapter bolts against FCA's 12 N-m specification and document any under-torque condition. If dye confirms a leak at the adapter-to-block interface, follow the current VIN- and model-year-specific FCA service information: the cited guidance calls for O-ring/gasket kit 68191356A$ rather than a complete adapter on covered vehicles other than model year 2014, and calls for adapter replacement on model year 2014. Transfer sensors only when the applicable replacement procedure requires it. Verify the exact suffix and current part by VIN before ordering. Do not buy a housing, cooler, seal kit, or aluminum conversion until the leak source and installed housing are confirmed.
Owner tips & cautions
- TipAsk the shop to show the dye-confirmed source: cap O-ring, adapter bolts, or the adapter-to-block interface. Those paths do not all require the same part.
- WarningDo not authorize a complete housing from oil in the valley alone. FCA specifically directs seal-only repair for a confirmed interface leak on covered non-2014 vehicles.
- WarningModel year 2014 is an exception in FCA's cited guidance. Confirm the VIN, model year, leak source, and current part suffix before ordering anything.
Sources for this issue (3)
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P26B7 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 P26B7 mean?
P26B7 stands for "Engine Coolant Bypass Valve "C" Control Circuit/Open." This code means the engine computer detected an open (broken) electrical circuit in the control wiring for engine coolant bypass valve 'C', so it cannot properly command that valve. The coolant bypass valve controls coolant flow through the engine to even out temperatures and reduce hot spots, staying closed when cold and opening as the engine warms. If the valve cannot be controlled, the engine can overheat or have poor heater performance, so this should be addressed before it leads to overheating damage.
What are the most common causes of P26B7?
The most common causes of P26B7 are: Open or broken wiring to the coolant bypass solenoid/valve C, Faulty coolant bypass valve/solenoid (internal open), Damaged, corroded, or disconnected connector, Blown fuse or poor ground in the control circuit, Chafed harness near the engine/bellhousing area, PCM/ECM driver fault (rare). The specific cause varies by vehicle.
How much does it cost to fix P26B7?
Repair costs for P26B7 range from $700 to $1,800, depending on the vehicle and root cause.
Which vehicles are affected by P26B7?
Au7o has documented P26B7 across 3 vehicle models from 2 manufacturers: Jaguar, Jeep.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.