Engine

P0370 — Timing Reference High Resolution Signal 'A' Malfunction

Severity: medium Drive with care, to a shop

What P0370 means

The engine control unit uses crankshaft and camshaft position sensor signals to know exactly where the pistons are, so it can time fuel injection and spark. P0370 is set when high resolution timing reference signal 'A' is missing, erratic or does not match what the PCM expects. The usual culprits are the crankshaft sensor, its wiring or the reluctor wheel.

Symptoms

  • Check engine light on
  • Rough or uneven idle
  • Misfires or hesitation under acceleration
  • Hard starting or no-start
  • Reduced power and worse fuel economy
  • Engine may stall unexpectedly

Possible causes

  1. Faulty crankshaft position sensor
  2. Damaged or corroded wiring or connectors in the signal circuit
  3. Damaged reluctor (timing) wheel with missing or broken teeth
  4. Faulty camshaft position sensor
  5. Incorrect sensor installation or wrong air gap
  6. PCM internal or software fault (uncommon)

How to diagnose

  1. Scan all codes and freeze frame data, and look for other CKP/CMP sensor codes
  2. Check that the scan tool shows RPM while cranking
  3. Inspect the crank sensor, connector and harness for chafing, oil, corrosion or breaks
  4. Test sensor power, ground and signal with a multimeter or scope
  5. Compare crankshaft and camshaft sensor waveforms
  6. Verify sensor air gap and that it is mounted securely
  7. Inspect the reluctor wheel for damaged teeth or metal debris
  8. Check timing belt or chain alignment if a jump in timing is suspected

Common fixes

  • Replace the crankshaft position sensor
  • Repair or replace damaged wiring and connectors
  • Replace the reluctor wheel or damaged timing components
  • Reflash or replace the PCM once it is confirmed faulty

Questions and answers

What does P0370 mean?

The PCM detected a fault in timing reference signal 'A', which comes from the crankshaft or camshaft sensors. Without a clean signal, fuel and spark timing can suffer.

Can I drive with P0370?

Only a short distance to a shop, and only if the engine runs well. Misfires, power loss and sudden stalling are possible, which is dangerous in traffic.

What most often causes P0370?

Most often a failed crankshaft position sensor or damaged wiring to it. A damaged reluctor wheel or the PCM are less common, so check the sensor and harness first.

This is general information about the code. The meaning can differ between makes and models: a scan tool and the repair manual for your car will show the exact cause.