Faulty crankshaft position sensor or its signal output; Damaged wiring, poor connections or corroded terminals in the sensor circuit; Faulty camshaft position sensor, or a signal that disagrees with the crankshaft signal; Damaged, dirty or loose reluctor or trigger wheel, or metallic debris on the sensor tip; Timing belt or chain stretched, jumped a tooth or incorrectly fitted; Low battery voltage or poor earth causing signal dropouts during cranking; Fault in the engine control unit.

P0370

Timing Reference High Resolution Signal A.

Generic
Powertrain
Generic code
High severity

How this code is built

P: SystemPowertrain
0: Defined bySAE, the same on every car
3: AreaIgnition system or misfire
70: FaultThe specific fault in that area

What it means

P0370 is the generic SAE J2012 code for a fault in the high resolution timing reference signal A. This is a signal that the engine control unit uses to work out crankshaft or camshaft position and speed very precisely. The code sets when the control unit sees that this signal is missing, erratic or out of step with other position inputs. How the signal is generated and which sensor is 'A' depends on the engine, so check the manufacturer data for the specific model.

Symptoms

Engine cranks but is hard to start or will not start
Misfires or rough running
Engine stalling or cutting out intermittently
Loss of power or hesitation under load
Malfunction indicator lamp on
Erratic or non-working rev counter

Possible causes

Faulty crankshaft position sensor or its signal outputlikely
Damaged wiring, poor connections or corroded terminals in the sensor circuitlikely
Faulty camshaft position sensor, or a signal that disagrees with the crankshaft signalpossible
Damaged, dirty or loose reluctor or trigger wheel, or metallic debris on the sensor tippossible
Timing belt or chain stretched, jumped a tooth or incorrectly fittedpossible
Low battery voltage or poor earth causing signal dropouts during crankingpossible
Fault in the engine control unitrare

How to diagnose

Read all stored and pending codes and note the freeze frame data, including engine speed, load and coolant temperature when the fault set
Check the battery condition and charging voltage, and inspect the main earths, as low voltage can upset position signals
Inspect the crankshaft and camshaft sensor wiring and connectors for chafing, oil contamination, water ingress, corrosion and loose pins
Inspect the sensor tips and mounting for debris, damage, correct fitting and air gap where the manufacturer specifies one
View live engine speed and cam/crank synchronisation data while cranking and running, checking for dropouts or a signal that disagrees
Test the sensor and circuit against manufacturer specifications, using a scope to check signal pattern, amplitude and missing or extra pulses
Inspect the trigger wheel for damage or movement, and verify the mechanical timing against the manufacturer's timing marks
Check supply voltage, earth and signal integrity at the control unit connector before suspecting the control unit

How to fix

Replace the faulty crankshaft or camshaft position sensor with a correct specification part
Repair or replace damaged wiring, connectors or terminals, and clean up any contamination
Replace or correctly refit a damaged or loose trigger wheel or reluctor ring
Correct the mechanical timing by renewing or refitting the belt or chain and associated components as the manufacturer specifies
Restore battery and earth integrity if low voltage or poor earths are found
Only after all else is ruled out, repair or replace the control unit, following the manufacturer's procedure

Can I keep driving?

High severity

Avoid driving the car, as it may stall without warning or fail to restart, and a timing fault can cause engine damage. If it is running normally, limit use to getting it to a workshop.

Guide written by AI from the code's definition. Confirm with a diagnosis before replacing parts.