Camshaft Position Sensor “A” Circuit Bank 1 or Single Sensor

Part of the generic P0340 overview — this page covers the Jeep meaning specifically.

What P0340 means

The WK2 Grand Cherokee PCM uses the camshaft position sensor signal in combination with the crankshaft position sensor (CKP) to synchronise fuel injection timing, ignition advance, and — on the 3.6L Pentastar — the variable valve timing (VVT) cam phaser actuation. P0340 indicates the PCM is not receiving a valid signal from the Bank 1 CMP sensor (Sensor 'A', intake side) for longer than the calibrated time-out period. On the 3.6L Pentastar V6, the Bank 1 CMP sensor is located on the rear cylinder head near the cam phaser. On the 5.7L HEMI V8, the single CMP sensor is mounted at the front of the engine block alongside the timing cover. A missing CMP signal typically causes a no-start condition because the PCM cannot determine the cylinder firing sequence; intermittent faults can cause stalling. The WK2 wiring harness in the engine bay is routed through high-heat zones near the firewall — insulation brittleness and chafed wires are a known issue on higher-mileage examples.

Symptoms

• Engine cranks but will not start (severe cases with complete signal loss)
• Check engine light on with P0340 stored
• Stalling or sudden power loss while driving
• Rough, erratic idle or misfires across multiple cylinders
• Possible VVT system fault — hesitation or poor throttle response on the 3.6L Pentastar

Common causes

• Failed Bank 1 camshaft position sensor — the most common cause, especially on high-mileage WK2 units
• Damaged or missing reluctor ring (tone ring) on the camshaft — worn, cracked, or missing teeth produce a distorted or absent signal
• Wiring harness damage — chafed insulation, broken wires, or corroded connector terminals in the CMP sensor circuit
• Corroded or loose CMP sensor connector — moisture intrusion in the engine bay is common on older WK2 models
• Cam phaser failure causing the camshaft to move outside the sensor's detection window (on Pentastar VVT engines)
• Faulty PCM input circuit — rare, but worth verifying after eliminating the sensor and wiring

Diagnostic approach

1. Read the CMP sensor signal live on a scan tool while cranking — A functioning CMP sensor should produce a rapidly pulsing signal during cranking. If the scan tool shows no CMP input while the CKP is reading normally, the fault is isolated to the CMP circuit. If both sensors show no signal, suspect the CKP or a power/ground issue common to both.
2. Inspect the CMP sensor connector and wiring harness — Unplug the Bank 1 CMP sensor connector and inspect for moisture, corrosion, or pushed-back terminals. On the WK2, the Pentastar rear CMP sensor wiring passes through a tight channel near the firewall — check for insulation chafing against the engine mount bracket. Clean corroded pins with electrical contact cleaner and test connector tension.
3. Test the sensor with a multimeter or oscilloscope — Check supply voltage (typically 5V reference from the PCM), ground continuity, and signal voltage at the sensor connector. A Hall-effect CMP sensor that passes voltage and ground checks but produces no signal pulse during cranking has an internal failure and should be replaced.
4. Inspect the camshaft reluctor ring for damage — On the 3.6L Pentastar, the cam reluctor ring is part of the cam phaser assembly. If oil sludge has damaged the phaser or if the cam has walked, the ring may no longer pass the sensor at the correct depth. If the sensor and wiring check out, inspect the reluctor ring for missing or damaged teeth using a borescope if possible.

Make & model notes

Jeep: WK2 Grand Cherokee 3.6L Pentastar: the Bank 1 CMP sensor (rear cylinder head) is accessed from above with the engine cover removed. The sensor connector is prone to moisture intrusion on older WK2 examples — inspect the pigtail connector thoroughly before condemning the sensor itself. Variable valve timing means a sludged cam phaser can also displace the camshaft outside the sensor range, so check oil condition if P0011 accompanies P0340.

Jeep: WK2 Grand Cherokee 5.7L HEMI: the CMP sensor is at the front of the engine near the timing cover and is easier to access than the Pentastar unit. HEMI engines do not use VVT on the WK2 platform, so phaser involvement is not a factor. The HEMI CMP sensor is a simple hall-effect unit — replacement is typically a straightforward swap.

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