Failed VVT solenoid B (open winding or internal short); Open circuit in the solenoid power feed or ground wire; Short to battery voltage on the solenoid control wire; Corroded, loose, or damaged electrical connector at the solenoid; Damaged wiring harness between the ECM and the solenoid (rubbed through, heat-damaged); Faulty ECM driver for the VVT solenoid circuit (least common)

DTC codes / Jaguar codes / P1398

P1398 · JaguarVariable Valve Timing Solenoid B Circuit High Input

Q: What does code P1398 mean?

Variable Valve Timing Solenoid B Circuit High Input. P1398 on a Jaguar means the engine control module (ECM) has detected an abnormally high voltage on the electrical circuit that controls the variable valve timing (VVT) solenoid for bank B. The ECM expects the solenoid to draw current and pull the signal voltage low when commanded, so a high-voltage reading tells the module the circuit is open, shorted to power, or the solenoid itself has failed.

P1398 on a Jaguar means the engine control module (ECM) has detected an abnormally high voltage on the electrical circuit that controls the variable valve timing (VVT) solenoid for bank B. The ECM expects the solenoid to draw current and pull the signal voltage low when commanded, so a high-voltage reading tells the module the circuit is open, shorted to power, or the solenoid itself has failed.

SystemPowertrain

Code typeJaguar specific

SeverityMedium

Fix difficultyIntermediate

AreaIgnition system and misfire

Symptoms you may notice

Illuminated check engine light, often with no other symptoms besides the warning light
Rough idle or unstable engine speed, especially when cold
Reduced engine performance and poor fuel economy due to incorrect cam timing
Sluggish acceleration or hesitation during light throttle
In rare cases, a no-start or hard-start condition if the cam timing is stuck in an adverse position

Common causes, most likely first

Failed VVT solenoid B (open winding or internal short)
Open circuit in the solenoid power feed or ground wire
Short to battery voltage on the solenoid control wire
Corroded, loose, or damaged electrical connector at the solenoid
Damaged wiring harness between the ECM and the solenoid (rubbed through, heat-damaged)
Faulty ECM driver for the VVT solenoid circuit (least common)

How to diagnose and fix it

Connect a scan tool and confirm P1398 is active, then command the VVT solenoid on and off while watching the circuit voltage to verify the fault is present.
Inspect the VVT solenoid B connector and wiring for corrosion, loose pins, or chafing, and repair any obvious damage before replacing parts.
Measure the resistance of the VVT solenoid B with a multimeter and compare it to the Jaguar specification for your engine; an open or shorted winding confirms a failed solenoid.
Check for battery voltage on the solenoid power feed with the key on and verify the ground circuit has less than 1 ohm resistance to the engine block.
Back-probe the control wire at the ECM and check for a short to power with the solenoid disconnected; repair the harness if a short is found.
If the wiring and solenoid test good, substitute a known-good VVT solenoid B and clear the code to see if it returns.
After any repair, clear the adaptive values, perform a road test, and confirm the code does not reset.

Why a high-voltage code is not always the solenoid

A high-voltage reading on a solenoid driver circuit most often means the circuit is open, so a broken wire or unplugged connector can set P1398 even when the solenoid itself is perfectly healthy.
Jaguar VVT solenoids are oil-controlled, and sludge or low oil pressure can make the solenoid stick, but a stuck solenoid usually sets a performance code rather than a high-input code; do not replace the solenoid for P1398 without checking the electrical circuit first.
The ECM driver for the VVT circuit can be damaged by a shorted solenoid, so always check solenoid resistance before installing a new ECM to avoid repeating the failure.
On some Jaguar engines, the VVT solenoid shares a power feed with other engine sensors, so a blown fuse or corroded splice can set P1398 along with other codes that seem unrelated.
Intermittent P1398 codes that appear only after the engine is hot often point to a harness that rubs against a hot component or a connector that loses tension when warm.

Can I keep driving with P1398?

You can usually drive the car short distances to a repair shop, but avoid hard acceleration and sustained high speeds because incorrect cam timing can cause poor performance and, in extreme cases, engine damage. If the engine runs very rough or stalls, stop driving and have the vehicle towed.

Tools that help

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Guidance is general and written for Jaguar vehicles. Exact tests and values vary by model, so confirm the fault before replacing parts.