P0335: P0335 Diagnostic Guide

What this code means

P0335 may mean the ECM is not seeing the crankshaft position sensor circuit signal it expects.

What the vehicle may do

The engine may crank and not start.
The engine may stall or stumble.
The engine may run rough or have poor driveability.

Possible fault areas

Possible crankshaft position sensor circuit issue.
Possible connector, terminal, or wiring issue.
Possible low reference, signal, or reference-voltage issue.
Possible sensor installation, reluctor, timing-drive, or engine oil condition.
Possible control module-side fault.

Diagnostic path

Opening context and monitor logic

On this 2014 to 2018 GMC Sierra 1500 with the 5.3 gas engine, P0335 is a crankshaft position sensor circuit code. In plain terms, the ECM may not be seeing the crank signal it expects. The truck may crank and not start, stall, stumble, or run poorly, and the broad fault areas can include the crank sensor circuit, connector and terminal condition, the 5 V reference, signal, low reference, sensor installation, reluctor relationship, timing-drive condition, or the control module side. Before getting deep, start with the basic system checks, then follow a structured diagnostic approach. Treat the run conditions as monitor gates. One listed gate includes MAF Sensor greater than 3 g/s, and once the gates are met, the P0335 monitor runs continuously. The code can set when the crankshaft position sensor has no signal for greater than 4 s, greater than 1 s, or during 2 engine revolution(s), depending on the operating case.

Initial scan-tool verification

With Ignition On / Vehicle In Service Mode, first make sure the shared 5-volt reference fault group is not active. If it is, handle that issue first instead of chasing the crank sensor by itself. Then run the engine and check whether a related crankshaft performance fault is active. If that performance fault is present, move into the circuit and system testing path. If it is not present, watch the Crankshaft Position Active Counter and verify that it increments. If the active counter does not increment, go to circuit and system testing. If it does increment, monitor the Crankshaft Position Resync Counter. It should stay at 0 Counts, and the engine should not stumble or stall while you wiggle the harness and connector at the B26 Crankshaft Position Sensor and at the K20 Engine Control Module. If the counter goes greater than 0 counts, repair the wiring, terminals, or electrical connectors as needed. If it stays at 0 counts, reproduce the operating conditions or the captured conditions and verify that P0335 does not reset.

Start circuit testing at the sensor connector

For circuit and system testing, turn the ignition and vehicle systems off, then disconnect the electrical connector at the B26 Crankshaft Position Sensor. Before doing continuity checks, remember that it may take up to 2 min for all vehicle systems to power down before an accurate ground or low reference circuit continuity test can be performed.

Low reference circuit checks

Start with the low reference side. Test for less than 10 Ω between low reference circuit terminal 2/B and ground. If that reading is 10 Ω or greater, disconnect the appropriate K20 Engine Control Module connector and test the low reference circuit end-to-end. You want less than 2 Ω between terminal 2/B at the component harness and the other end of the circuit at the control module harness. If it is 2 Ω or greater, repair the open or high resistance in that circuit. If it is less than 2 Ω, the path calls for replacing the K20 Engine Control Module. If the original low reference test was already less than 10 Ω, move on to the 5 V reference test.

5 V reference circuit checks

With Ignition On / Vehicle In Service Mode, test the 5 V reference circuit at terminal 3/C to ground. The correct range is 4.8 to 5.2 V. If it is less than 4.8 V, turn the ignition and vehicle off, disconnect the appropriate K20 Engine Control Module connector, and test for infinite resistance from 5 V reference terminal 3/C at the component harness to ground. If resistance is less than infinite, repair the short to ground. If it is infinite, test that 5 V reference circuit end-to-end and look for less than 2 Ω. If it is 2 Ω or greater, repair the open or high resistance. If it is less than 2 Ω, the path calls for replacing the K20 Engine Control Module. If the 5 V reference is greater than 5.2 V, turn the ignition and vehicle off, disconnect the appropriate K20 Engine Control Module connector, turn Ignition On / Vehicle In Service Mode, and test for less than 1 V from terminal 3/C at the component harness to ground. If it is 1 V or greater, repair the short to voltage. If it is less than 1 V, the path calls for replacing the K20 Engine Control Module. If the 5 V reference is within 4.8 to 5.2 V, continue to the signal circuit test.

Signal circuit simulation and checks

With the 5 V reference in range, rapidly tap a 3 A fused jumper wire between signal circuit terminal 1/A and ground while watching the Crankshaft Position Active Counter. The counter should increment. If it does not increment, turn the ignition and vehicle off, disconnect the appropriate K20 Engine Control Module connector, turn Ignition On / Vehicle In Service Mode, and test for less than 1 V between signal circuit terminal 1/A at the component harness and ground. If it is 1 V or greater, repair the short to voltage. If it is less than 1 V, turn the ignition and vehicle off and test for infinite resistance from that same signal circuit terminal to ground. If resistance is less than infinite, repair the short to ground. If it is infinite, test the signal circuit end-to-end. You want less than 2 Ω between terminal 1/A at the component harness and the other end of the circuit at the control module harness. If it is 2 Ω or greater, repair the open or high resistance. If it is less than 2 Ω, the path calls for replacing the K20 Engine Control Module.

When the circuit responds correctly

If the Crankshaft Position Active Counter does increment during the signal test, check that the related crankshaft performance fault is not active. If it is not active, the path moves to testing or replacing the B26 Crankshaft Position Sensor. If that performance fault is active, do not jump straight to the sensor. Check for the listed mechanical and installation problems: crank sensor and reluctor play, debris between the components, air gap or installation problems, looseness, visible damage, worn or damaged camshaft or crankshaft sprockets, contaminated or dirty engine oil, and worn or damaged timing-drive components or tensioners. If one of those conditions is found, repair or replace as necessary. If none are found, the path moves to testing or replacing the B26 Crankshaft Position Sensor.

Repair verification and takeaway

After the repair is complete, keep verification separate from the testing path. Verify the repair and confirm the code stays gone under the proper operating conditions. The takeaway on P0335 is simple: prove the low reference, 5 V reference, and signal circuit first, then let the counters and follow-up checks decide whether you are dealing with wiring, connector issues, the sensor, mechanical sync concerns, or the module side. For more diagnostic training, visit stepdiagnostics.com.