P0342: Camshaft Position Sensor A Circuit Low Input (Bank 1)

What it means

The CMP signal voltage is below the lower threshold. Most often a sensor with degraded internal output or a short to ground.

At a glance

• Usually lights the check-engine light
• Affects emissions; the car can fail an emissions test

How it works

Camshaft Position Sensor A on bank 1, or the single cam sensor on a one-bank engine, sends a position signal to the engine control module. This code means the signal voltage is below the module's lower limit, commonly from a failing sensor, a signal wire shorted to ground, or poor connector contact.

Common causes

Most likely first.

1. Sensor failed
2. Signal shorted to ground
3. Connector pins corroded - high contact resistance

Symptoms

• Check engine light on
• Power loss especially in mid-rpm range
• Possible rough idle or stalling
• Increased fuel consumption

How to diagnose it

1. Record freeze-frame data and check live Sensor A data for bank 1 to confirm the low input and whether it changes during cranking.
2. Locate Sensor A using service information and inspect its connector for corrosion, damaged pins, or a loose fit.
3. Inspect the bank 1 sensor harness for chafing or damage, especially where it could contact ground or hot engine parts.
4. Test the Sensor A circuit for a short to ground and check continuity and pin contact against the manufacturer's specification.
5. If the circuit checks out, test Sensor A itself and check for related crankshaft or cam timing codes.

Common fixes

• Clean and reconnect a corroded or loose Sensor A connector.
• Repair the Sensor A signal wire if it is shorted to ground or damaged.
• Restore or replace a damaged connector pin.
• Replace Sensor A on bank 1 if it fails the manufacturer's tests.

Can I keep driving?

A low cam sensor signal can cause power loss, rough running, or stalling, so limit driving and avoid situations where a stall would be hazardous. Stop if the engine repeatedly stalls or becomes difficult to control.