Symptoms
Symptoms of a P2012 code may include:
- Hesitation during acceleration
- Reduced engine performance, especially at low RPM
- Rich or lean exhaust
- Decreased fuel efficiency
- Engine surging
Causes
Possible causes of this engine code include:
- Loose or binding intake manifold runners, bank 2
- Faulty IMRC actuator solenoid, bank 2
- Faulty intake manifold runner position sensor, bank 2
- Open or shorted wiring in the IMRC actuator solenoid control circuit
- Carbon buildup on IMRC flaps or intake manifold ports
- Faulty MAP sensor
- Corroded IMRC actuator solenoid connector face
Diagnostic and Repair Procedures
When attempting to diagnose a P2012 code, a diagnostic scanner, a digital volt/ohmmeter (DVOM), and a reliable vehicle information source will be essential. It is wise to check Technical Service Bulletins (TSBs) for specific symptoms, stored codes, and the vehicle’s make and model before any diagnosis. If you find a related TSB, the information will often help diagnose the code in question, as TSBs are packed with thousands of repairs.
A fantastic starting point for any diagnosis is a visual inspection of the system’s wiring and connector faces. Knowing that IMRC actuator connectors are prone to corrosion, which could cause an open circuit, one might focus attention on this area.
You can proceed by connecting the scanner to the vehicle’s diagnostic connector and retrieving all stored codes and freeze frame data. Writing down this information, in case it’s an intermittent code, is a good practice. Now, clear the codes and test-drive the vehicle to see if the code resets.
Continuing, if the code resets, access the IMRC actuator solenoid and IMRC runner position sensor. Consult your vehicle information source for testing specifications and use the DVOM to perform resistance tests on the solenoid and sensor. If any of these components do not meet specifications, replace them and retest the system.
To prevent damage to the PCM, disconnect all associated controllers before testing circuit resistance with the DVOM. Use the DVOM to test resistance and continuity on all system circuits if the actuator and sensor resistance levels meet manufacturer specifications. Short or open circuits will need to be repaired or replaced as necessary.
Additional Diagnostic Notes:
- Carbon coking inside the intake manifold walls can cause IMRC flaps to bind
- Be cautious when handling small screws or rivets in or near intake manifold openings
- Test IMRC flap binding with the actuator disconnected from the shaft
- Screws (or rivets) that secure the flaps to the shaft may loosen or fall out, causing the flaps to jam