Parts for your 2012 Toyota Mark x-Crank angle sensor

2012 Toyota Mark X crank angle sensor: what it does and when to service it

Yes, the 2012 Toyota Mark X is fitted with a crank angle sensor (commonly called the crankshaft position sensor, CKP). This is documented in Toyota’s GRX13# Repair Manual for the 4GR‑FSE and 2GR‑FSE engines, the Toyota Electronic Parts Catalogue listing for the GRX130/133 series, and the Toyota DTC set that includes P0335/P0339 for the CKP circuit. So it’s absolutely relevant on this model.

The sensor’s job is to read a toothed wheel on the crank and feed exact engine speed and crank position back to the ECU. That data syncs fuel injection and spark timing with the cam sensors, lets the engine fire up smartly, and keeps performance, emissions, and economy in the sweet spot. If the CKP signal drops out, the ECU can’t time anything properly, which is why a faulty sensor can cause long cranking or a no‑start.

It’s not a scheduled replacement item on the Mark X, but it deserves a look during major services—especially if there are oil leaks nearby or the car’s seen a lot of heat and road grime. On the GR V6 it’s mounted low at the back of the block near the transmission bellhousing, reading the crank reluctor. A scan tool check for stable RPM while cranking is a handy first test of CKP health.

• Typical symptoms: hard starting or no start, intermittent stalling at idle or when hot, rough running, poor fuel use, hesitation, and a check‑engine light with codes like P0335 or P0339.
• Quick service tips: inspect the wiring and connector for oil intrusion or chafing, ensure the sensor isn’t covered in metal fuzz, and confirm the engine earths are clean and tight.

Replacement is straightforward for a competent technician: disconnect the battery, safely raise the vehicle, access the sensor from underneath, unplug it, remove the retaining bolt, and ease the sensor out (it’s O‑ringed). Lightly oil the new O‑ring, install the new unit, and tighten the bolt to workshop‑manual spec. Clear any fault codes and road‑test. Genuine or high‑quality aftermarket sensors are recommended, cheap units can cause ghost faults or hot‑soak issues. No special relearn is typically required on Toyota GR engines—the ECU adapts once it sees a clean signal—but using a scan tool to confirm stable CKP and cam sync is good practice.

Popular questions

Where is the crank angle sensor on a 2012 Toyota Mark X?
The CKP sits low at the rear of the 4GR‑FSE/2GR‑FSE V6, right by the transmission bellhousing. It reads a toothed wheel on the crank. Access is usually from underneath after removing undertrays.

A torch and small mirror help spot the single retaining bolt and connector. Expect limited space around exhaust and driveline components.

What are the signs the CKP is failing on a Mark X?
Common clues include long cranking or a no‑start, random stalling when hot, rough idle, and a check‑engine light with P0335 or P0339. Fuel economy may dip and the engine can feel gutless under load.

Always rule out basics first—battery condition, earths, and cam sensor faults—because they can mimic CKP issues.

Does the CKP need programming after replacement?
On Toyota GR engines, a CKP relearn isn’t normally required. Fit the new sensor, clear codes, and verify with a scan tool that engine RPM reads correctly and cam/crank sync is stable.

If faults return, check connector tension, wiring integrity, and ensure the sensor is seated fully with the O‑ring correctly installed.