Honda's R20A is a 2-litre, 16-valve SOHC i-VTEC petrol four built from 2006 to 2012, making 150-156 hp and 190-193 Nm. It powers the eighth-generation Civic FK/FN and the CR-V RE. In the workshop it tends to turn up for three reasons: VTEC that will not engage because the solenoid screen or oil pressure switch is sludged, oil burning through the rings at high mileage when the wrong viscosity has been used, and a short cold-start rattle from a chain tensioner that loses its prime. CR-V variants fitted with EGR can also idle rough from a carboned EGR passage. This page gives torque figures for the cylinder head bolts, crankshaft pulley bolt, camshaft sprocket bolt, oil drain plug and intake manifold bolts, plus chain, oil and coolant service data.
For a VTEC fault or P2646/P2647, measure oil pressure at the switch port with a mechanical gauge before replacing the solenoid; a worn pump or blocked pickup sets the same codes. For oil consumption, run dry and wet compression tests to separate ring wear from other causes. Idle hunting after throttle body cleaning or a battery disconnect usually needs the idle relearn, not a vacuum leak hunt.
Check first
Pull the VTEC solenoid screen and check it for sludge; it follows stretched oil change intervals.
Warm idle oil pressure at the switch port must be at least 49 kPa, or the solenoid is not the fault.
A cold-start rattle lasting 3-8 seconds points to the chain tensioner, not rod knock.
A wet test raising compression by more than 2 bar on any cylinder confirms ring wear.
Check the oil is 0W-20 or 5W-20; heavier oil worsens drain-back and ring scoring.
i-VTEC solenoid spool valve clogging at 80,000-120,000 km: oil sludge blocks the VTEC oil pressure switch and solenoid screen, causing VTEC engagement failure (engine stays in low-cam mode), CEL P2646/P2647, loss of top-end power above 5,500 rpm. Root cause is extended oil change intervals or use of non-Honda spec oil. Preventable with 10,000 km oil changes.
Oil consumption via piston rings at 150,000-200,000 km: R20A piston rings develop micro-scoring on cylinder walls when run on incorrect viscosity oil (e.g. 10W-40 instead of 0W-20/5W-20). Symptoms: blue smoke on startup and deceleration, consumption >0.5L/1,000 km, fouled spark plugs. Compression test typically shows 10-12 bar (low normal). Fix requires piston ring replacement or short block;
Timing chain tensioner rattle on cold start at 100,000-160,000 km: The hydraulic chain tensioner loses prime after extended cold soak, producing a metallic rattle for 3-8 seconds on startup. Root cause is tensioner check valve wear and oil drain-back. Distinct from rod knock — rattle disappears once oil pressure builds. Continued neglect leads to chain guide wear and eventual chain skip. Use Honda Genuine 0W-20 or 5W-20 to minimize drain-back.
EGR valve carbon fouling at 90,000-130,000 km (CR-V RE market variants with EGR): EGR passage accumulates hard carbon deposits causing rough idle, hesitation at 1,500-2,500 rpm, and occasional P0401/P0404 codes. Root cause is short-trip urban driving cycles. Cleaning is effective if valve seat is not pitted.
Alternator bearing failure at 120,000-180,000 km: The Denso alternator fitted to R20A develops bearing noise (high-pitched whine varying with engine speed) followed by charging failure. Root cause is heat soak from SOHC exhaust routing proximity. Symptoms: battery warning light, voltage drop to <13.5V at idle. Check serpentine belt condition simultaneously — belt often glazed by bearing-induced vibration.
Throttle body carbon buildup causing idle surge at 80,000-120,000 km: the drive-by-wire throttle body accumulates carbon from PCV oil vapor deposits, causing erratic idle and stalling. Clean with throttle body cleaner (not carb cleaner, which can damage the DBW bore coating) and perform the idle relearn procedure afterward.
Knock sensor false codes P0325/P0328 at 60,000-100,000 km: The single knock sensor mounted on the block develops intermittent open-circuit faults due to connector corrosion (particularly in salt-belt markets). Symptoms: CEL, ECM retards ignition timing causing 5-8% fuel economy loss and slight power reduction. Root cause is connector seal failure allowing moisture ingress. Fix: clean connector with electrical contact cleaner, apply dielectric grease, clear codes.
180 Nm (no angle — reusable bolt, but verify thread condition; use Honda tool 07JAB-001020A to hold crank) unconfirmed
Camshaft Sprocket Bolt
55 Nm — hold cam with open-end wrench on hex flat, do not use impact unconfirmed
Oil Drain Plug
45 Nm — replace crush washer every service (Honda p/n 94109-14000) unconfirmed
Intake Manifold Bolts
20 Nm in cross pattern, two passes unconfirmed
Figures marked unconfirmed could not be cross-checked against a workshop source. Verify against the vehicle’s own documentation before tightening.
Service intervals
Timing Chain
No scheduled replacement — inspect at 160,000 km; replace if stretch exceeds 0.5% elongation or guide wear is visible
Oil Change Km
10000
Oil Spec
Honda Genuine 0W-20 or 5W-20 API SN/SM (Honda HTO-06 spec); 5W-30 ACEA A1/B1 acceptable in high-ambient markets
Oil Capacity L
4.4
Coolant Spec
Honda Type 2 Blue Long Life Coolant (OAT, silicate-free); 50/50 premix; do NOT mix with green IAT coolant
Pro tips from the field
The R20A idle relearn procedure is mandatory after any throttle body cleaning, battery disconnect, or ECM reset — failure to perform it results in persistent idle hunting that is frequently misdiagnosed as a vacuum leak or IACV fault. Procedure: with engine fully warm, all accessories OFF, transmission in Park/Neutral, let idle stabilize for 10 minutes without touching throttle. The ECM stores the base idle position; skipping this step wastes diagnostic time.
When diagnosing P2646 (VTEC oil pressure switch low voltage), always check oil pressure at the switch port with a mechanical gauge before condemning the solenoid. A worn oil pump or blocked pickup screen will produce identical codes. R20A oil pressure spec is minimum 49 kPa (0.5 kgf/cm²) at idle warm — if pressure is low, solenoid replacement will not fix the fault.
On high-mileage R20A engines, perform a wet compression test alongside dry: if wet test raises compression by more than 2 bar on any cylinder, ring wear is confirmed and VTEC solenoid cleaning will not restore top-end performance.
Honda specifies Loctite 5699 (grey RTV) for the timing chain cover-to-block sealing surface — do not substitute with generic RTV. The cover has a complex multi-surface joint at the oil pan rail and block face; incorrect sealant bead width (should be 3mm) or wrong product causes oil seepage that is misdiagnosed as rear main seal failure. Apply sealant and torque cover within 4 minutes of application.
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TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
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